[PATCH v2 0/4] sysctl: Remove sentinel elements from networking

Joel Granados via B4 Relay posted 4 patches 1 month ago
Failed in applying to current master (apply log)
There is a newer version of this series
net/appletalk/sysctl_net_atalk.c        | 1 -
net/ax25/sysctl_net_ax25.c              | 4 +---
net/bridge/br_netfilter_hooks.c         | 1 -
net/core/neighbour.c                    | 5 +----
net/core/sysctl_net_core.c              | 9 ++++-----
net/dccp/sysctl.c                       | 2 --
net/ieee802154/6lowpan/reassembly.c     | 6 +-----
net/ipv4/devinet.c                      | 5 ++---
net/ipv4/ip_fragment.c                  | 2 --
net/ipv4/route.c                        | 8 ++------
net/ipv4/sysctl_net_ipv4.c              | 7 +++----
net/ipv4/xfrm4_policy.c                 | 1 -
net/ipv6/addrconf.c                     | 5 +----
net/ipv6/icmp.c                         | 1 -
net/ipv6/netfilter/nf_conntrack_reasm.c | 1 -
net/ipv6/reassembly.c                   | 2 --
net/ipv6/route.c                        | 5 -----
net/ipv6/sysctl_net_ipv6.c              | 4 +---
net/ipv6/xfrm6_policy.c                 | 1 -
net/llc/sysctl_net_llc.c                | 8 ++------
net/mpls/af_mpls.c                      | 3 +--
net/mptcp/ctrl.c                        | 1 -
net/netfilter/ipvs/ip_vs_ctl.c          | 5 +----
net/netfilter/ipvs/ip_vs_lblc.c         | 5 +----
net/netfilter/ipvs/ip_vs_lblcr.c        | 5 +----
net/netfilter/nf_conntrack_standalone.c | 6 +-----
net/netfilter/nf_log.c                  | 3 +--
net/netrom/sysctl_net_netrom.c          | 1 -
net/phonet/sysctl.c                     | 1 -
net/rds/ib_sysctl.c                     | 1 -
net/rds/sysctl.c                        | 1 -
net/rds/tcp.c                           | 1 -
net/rose/sysctl_net_rose.c              | 1 -
net/rxrpc/sysctl.c                      | 1 -
net/sctp/sysctl.c                       | 6 +-----
net/smc/smc_sysctl.c                    | 1 -
net/sunrpc/sysctl.c                     | 1 -
net/sunrpc/xprtrdma/svc_rdma.c          | 1 -
net/sunrpc/xprtrdma/transport.c         | 1 -
net/sunrpc/xprtsock.c                   | 1 -
net/tipc/sysctl.c                       | 1 -
net/unix/sysctl_net_unix.c              | 1 -
net/x25/sysctl_net_x25.c                | 1 -
net/xfrm/xfrm_sysctl.c                  | 5 +----
44 files changed, 26 insertions(+), 106 deletions(-)
[PATCH v2 0/4] sysctl: Remove sentinel elements from networking
Posted by Joel Granados via B4 Relay 1 month ago
From: Joel Granados <j.granados@samsung.com>

What?
These commits remove the sentinel element (last empty element) from the
sysctl arrays of all the files under the "net/" directory that register
a sysctl array. The merging of the preparation patches [4] to mainline
allows us to just remove sentinel elements without changing behavior.
This is safe because the sysctl registration code (register_sysctl() and
friends) use the array size in addition to checking for a sentinel [1].

Why?
By removing the sysctl sentinel elements we avoid kernel bloat as
ctl_table arrays get moved out of kernel/sysctl.c into their own
respective subsystems. This move was started long ago to avoid merge
conflicts; the sentinel removal bit came after Mathew Wilcox suggested
it to avoid bloating the kernel by one element as arrays moved out. This
patchset will reduce the overall build time size of the kernel and run
time memory bloat by about ~64 bytes per declared ctl_table array (more
info here [5]).

When are we done?
There are 4 patchest (25 commits [2]) that are still outstanding to
completely remove the sentinels: files under "net/" (this patchset),
files under "kernel/" dir, misc dirs (files under mm/ security/ and
others) and the final set that removes the unneeded check for ->procname
== NULL.

Testing:
* Ran sysctl selftests (./tools/testing/selftests/sysctl/sysctl.sh)
* Ran this through 0-day with no errors or warnings

Savings in vmlinux:
  A total of 64 bytes per sentinel is saved after removal; I measured in
  x86_64 to give an idea of the aggregated savings. The actual savings
  will depend on individual kernel configuration.
    * bloat-o-meter
        - The "yesall" config saves 3976 bytes (bloat-o-meter output [6])
        - A reduced config [3] saves 1263 bytes (bloat-o-meter output [7])

Savings in allocated memory:
  None in this set but will occur when the superfluous allocations are
  removed from proc_sysctl.c. I include it here for context. The
  estimated savings during boot for config [3] are 6272 bytes. See [8]
  for how to measure it.

Comments/feedback greatly appreciated

Changes in v2:
- Rebased to v6.9-rc1
- Removed unneeded comment from sysctl_net_ax25.c
- Link to v1: https://lore.kernel.org/r/20240314-jag-sysctl_remset_net-v1-0-aa26b44d29d9@samsung.com

Best
Joel

[1] https://lore.kernel.org/all/20230809105006.1198165-1-j.granados@samsung.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/joel.granados/linux.git/tag/?h=sysctl_remove_empty_elem_v5
[3] https://gist.github.com/Joelgranados/feaca7af5537156ca9b73aeaec093171
[4] https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/

[5]
Links Related to the ctl_table sentinel removal:
* Good summaries from Luis:
  https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/
  https://lore.kernel.org/all/ZMFizKFkVxUFtSqa@bombadil.infradead.org/
* Patches adjusting sysctl register calls:
  https://lore.kernel.org/all/20230302204612.782387-1-mcgrof@kernel.org/
  https://lore.kernel.org/all/20230302202826.776286-1-mcgrof@kernel.org/
* Discussions about expectations and approach
  https://lore.kernel.org/all/20230321130908.6972-1-frank.li@vivo.com
  https://lore.kernel.org/all/20220220060626.15885-1-tangmeng@uniontech.com

[6]
add/remove: 0/1 grow/shrink: 2/67 up/down: 76/-4052 (-3976)
Function                                     old     new   delta
llc_sysctl_init                              306     377     +71
nf_log_net_init                              866     871      +5
sysctl_core_net_init                         375     366      -9
lowpan_frags_init_net                        618     598     -20
ip_vs_control_net_init_sysctl               2446    2422     -24
sysctl_route_net_init                        521     493     -28
__addrconf_sysctl_register                   678     650     -28
xfrm_sysctl_init                             405     374     -31
mpls_net_init                                367     334     -33
sctp_sysctl_net_register                     386     346     -40
__ip_vs_lblcr_init                           546     501     -45
__ip_vs_lblc_init                            546     501     -45
neigh_sysctl_register                       1011     958     -53
mpls_dev_sysctl_register                     475     419     -56
ipv6_route_sysctl_init                       450     394     -56
xs_tunables_table                            448     384     -64
xr_tunables_table                            448     384     -64
xfrm_table                                   320     256     -64
xfrm6_policy_table                           128      64     -64
xfrm4_policy_table                           128      64     -64
x25_table                                    448     384     -64
vs_vars                                     1984    1920     -64
unix_table                                   128      64     -64
tipc_table                                   448     384     -64
svcrdma_parm_table                           832     768     -64
smc_table                                    512     448     -64
sctp_table                                   256     192     -64
sctp_net_table                              2304    2240     -64
rxrpc_sysctl_table                           704     640     -64
rose_table                                   704     640     -64
rds_tcp_sysctl_table                         192     128     -64
rds_sysctl_rds_table                         384     320     -64
rds_ib_sysctl_table                          384     320     -64
phonet_table                                 128      64     -64
nr_table                                     832     768     -64
nf_log_sysctl_table                          768     704     -64
nf_log_sysctl_ftable                         128      64     -64
nf_ct_sysctl_table                          3200    3136     -64
nf_ct_netfilter_table                        128      64     -64
nf_ct_frag6_sysctl_table                     256     192     -64
netns_core_table                             320     256     -64
net_core_table                              2176    2112     -64
neigh_sysctl_template                       1416    1352     -64
mptcp_sysctl_table                           576     512     -64
mpls_dev_table                               128      64     -64
lowpan_frags_ns_ctl_table                    256     192     -64
lowpan_frags_ctl_table                       128      64     -64
llc_station_table                             64       -     -64
llc2_timeout_table                           320     256     -64
ipv6_table_template                         1344    1280     -64
ipv6_route_table_template                    768     704     -64
ipv6_rotable                                 320     256     -64
ipv6_icmp_table_template                     448     384     -64
ipv4_table                                  1024     960     -64
ipv4_route_table                             832     768     -64
ipv4_route_netns_table                       320     256     -64
ipv4_net_table                              7552    7488     -64
ip6_frags_ns_ctl_table                       256     192     -64
ip6_frags_ctl_table                          128      64     -64
ip4_frags_ns_ctl_table                       320     256     -64
ip4_frags_ctl_table                          128      64     -64
devinet_sysctl                              2184    2120     -64
debug_table                                  384     320     -64
dccp_default_table                           576     512     -64
ctl_forward_entry                            128      64     -64
brnf_table                                   448     384     -64
ax25_param_table                             960     896     -64
atalk_table                                  320     256     -64
addrconf_sysctl                             3904    3840     -64
vs_vars_table                                256     128    -128
Total: Before=440631035, After=440627059, chg -0.00%

[7]
add/remove: 0/0 grow/shrink: 1/22 up/down: 8/-1263 (-1255)
Function                                     old     new   delta
sysctl_route_net_init                        189     197      +8
__addrconf_sysctl_register                   306     294     -12
ipv6_route_sysctl_init                       201     185     -16
neigh_sysctl_register                        385     366     -19
unix_table                                   128      64     -64
netns_core_table                             256     192     -64
net_core_table                              1664    1600     -64
neigh_sysctl_template                       1416    1352     -64
ipv6_table_template                         1344    1280     -64
ipv6_route_table_template                    768     704     -64
ipv6_rotable                                 192     128     -64
ipv6_icmp_table_template                     448     384     -64
ipv4_table                                   768     704     -64
ipv4_route_table                             832     768     -64
ipv4_route_netns_table                       320     256     -64
ipv4_net_table                              7040    6976     -64
ip6_frags_ns_ctl_table                       256     192     -64
ip6_frags_ctl_table                          128      64     -64
ip4_frags_ns_ctl_table                       320     256     -64
ip4_frags_ctl_table                          128      64     -64
devinet_sysctl                              2184    2120     -64
ctl_forward_entry                            128      64     -64
addrconf_sysctl                             3392    3328     -64
Total: Before=8523801, After=8522546, chg -0.01%

[8]
To measure the in memory savings apply this on top of this patchset.

"
diff --git i/fs/proc/proc_sysctl.c w/fs/proc/proc_sysctl.c
index 37cde0efee57..896c498600e8 100644
--- i/fs/proc/proc_sysctl.c
+++ w/fs/proc/proc_sysctl.c
@@ -966,6 +966,7 @@ static struct ctl_dir *new_dir(struct ctl_table_set *set,
        table[0].procname = new_name;
        table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
        init_header(&new->header, set->dir.header.root, set, node, table, 1);
+       printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table));

        return new;
 }
@@ -1189,6 +1190,7 @@ static struct ctl_table_header *new_links(struct ctl_dir *dir, s>
                link_name += len;
                link++;
        }
+       printk("%ld sysctl saved mem kzalloc\n", sizeof(struct ctl_table));
        init_header(links, dir->header.root, dir->header.set, node, link_table,
                    head->ctl_table_size);
        links->nreg = nr_entries;
"
and then run the following bash script in the kernel:

accum=0
for n in $(dmesg | grep kzalloc | awk '{print $3}') ; do
    accum=$(calc "$accum + $n")
done
echo $accum

Signed-off-by: Joel Granados <j.granados@samsung.com>

--

---
---
Joel Granados (4):
      networking: Remove the now superfluous sentinel elements from ctl_table array
      netfilter: Remove the now superfluous sentinel elements from ctl_table array
      appletalk: Remove the now superfluous sentinel elements from ctl_table array
      ax.25: Remove the now superfluous sentinel elements from ctl_table array

 net/appletalk/sysctl_net_atalk.c        | 1 -
 net/ax25/sysctl_net_ax25.c              | 4 +---
 net/bridge/br_netfilter_hooks.c         | 1 -
 net/core/neighbour.c                    | 5 +----
 net/core/sysctl_net_core.c              | 9 ++++-----
 net/dccp/sysctl.c                       | 2 --
 net/ieee802154/6lowpan/reassembly.c     | 6 +-----
 net/ipv4/devinet.c                      | 5 ++---
 net/ipv4/ip_fragment.c                  | 2 --
 net/ipv4/route.c                        | 8 ++------
 net/ipv4/sysctl_net_ipv4.c              | 7 +++----
 net/ipv4/xfrm4_policy.c                 | 1 -
 net/ipv6/addrconf.c                     | 5 +----
 net/ipv6/icmp.c                         | 1 -
 net/ipv6/netfilter/nf_conntrack_reasm.c | 1 -
 net/ipv6/reassembly.c                   | 2 --
 net/ipv6/route.c                        | 5 -----
 net/ipv6/sysctl_net_ipv6.c              | 4 +---
 net/ipv6/xfrm6_policy.c                 | 1 -
 net/llc/sysctl_net_llc.c                | 8 ++------
 net/mpls/af_mpls.c                      | 3 +--
 net/mptcp/ctrl.c                        | 1 -
 net/netfilter/ipvs/ip_vs_ctl.c          | 5 +----
 net/netfilter/ipvs/ip_vs_lblc.c         | 5 +----
 net/netfilter/ipvs/ip_vs_lblcr.c        | 5 +----
 net/netfilter/nf_conntrack_standalone.c | 6 +-----
 net/netfilter/nf_log.c                  | 3 +--
 net/netrom/sysctl_net_netrom.c          | 1 -
 net/phonet/sysctl.c                     | 1 -
 net/rds/ib_sysctl.c                     | 1 -
 net/rds/sysctl.c                        | 1 -
 net/rds/tcp.c                           | 1 -
 net/rose/sysctl_net_rose.c              | 1 -
 net/rxrpc/sysctl.c                      | 1 -
 net/sctp/sysctl.c                       | 6 +-----
 net/smc/smc_sysctl.c                    | 1 -
 net/sunrpc/sysctl.c                     | 1 -
 net/sunrpc/xprtrdma/svc_rdma.c          | 1 -
 net/sunrpc/xprtrdma/transport.c         | 1 -
 net/sunrpc/xprtsock.c                   | 1 -
 net/tipc/sysctl.c                       | 1 -
 net/unix/sysctl_net_unix.c              | 1 -
 net/x25/sysctl_net_x25.c                | 1 -
 net/xfrm/xfrm_sysctl.c                  | 5 +----
 44 files changed, 26 insertions(+), 106 deletions(-)
---
base-commit: 4cece764965020c22cff7665b18a012006359095
change-id: 20240311-jag-sysctl_remset_net-d403a1a93d6b

Best regards,
-- 
Joel Granados <j.granados@samsung.com>
[PATCH v2 1/4] networking: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados via B4 Relay 1 month ago
From: Joel Granados <j.granados@samsung.com>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

* Remove sentinel element from ctl_table structs.
* Remove extra element in ctl_table arrays declarations
* Remove instances where an array element is zeroed out to make it look
  like a sentinel. This is not longer needed and is safe after commit
  c899710fe7f9 ("networking: Update to register_net_sysctl_sz") added
  the array size to the ctl_table registration
* Replace the for loop stop condition that tests for procname == NULL with
  one that depends on array size
* Removed the "-1" that adjusted for having an extra empty element when
  looping over ctl_table arrays
* Removing the unprivileged user check in ipv6_route_sysctl_init is
  safe as it is replaced by calling ipv6_route_sysctl_table_size;
  introduced in commit c899710fe7f9 ("networking: Update to
  register_net_sysctl_sz")
* Replace empty array registration with the register_net_sysctl_sz call.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 net/core/neighbour.c                | 5 +----
 net/core/sysctl_net_core.c          | 9 ++++-----
 net/dccp/sysctl.c                   | 2 --
 net/ieee802154/6lowpan/reassembly.c | 6 +-----
 net/ipv4/devinet.c                  | 5 ++---
 net/ipv4/ip_fragment.c              | 2 --
 net/ipv4/route.c                    | 8 ++------
 net/ipv4/sysctl_net_ipv4.c          | 7 +++----
 net/ipv4/xfrm4_policy.c             | 1 -
 net/ipv6/addrconf.c                 | 5 +----
 net/ipv6/icmp.c                     | 1 -
 net/ipv6/reassembly.c               | 2 --
 net/ipv6/route.c                    | 5 -----
 net/ipv6/sysctl_net_ipv6.c          | 4 +---
 net/ipv6/xfrm6_policy.c             | 1 -
 net/llc/sysctl_net_llc.c            | 8 ++------
 net/mpls/af_mpls.c                  | 3 +--
 net/mptcp/ctrl.c                    | 1 -
 net/netrom/sysctl_net_netrom.c      | 1 -
 net/phonet/sysctl.c                 | 1 -
 net/rds/ib_sysctl.c                 | 1 -
 net/rds/sysctl.c                    | 1 -
 net/rds/tcp.c                       | 1 -
 net/rose/sysctl_net_rose.c          | 1 -
 net/rxrpc/sysctl.c                  | 1 -
 net/sctp/sysctl.c                   | 6 +-----
 net/smc/smc_sysctl.c                | 1 -
 net/sunrpc/sysctl.c                 | 1 -
 net/sunrpc/xprtrdma/svc_rdma.c      | 1 -
 net/sunrpc/xprtrdma/transport.c     | 1 -
 net/sunrpc/xprtsock.c               | 1 -
 net/tipc/sysctl.c                   | 1 -
 net/unix/sysctl_net_unix.c          | 1 -
 net/x25/sysctl_net_x25.c            | 1 -
 net/xfrm/xfrm_sysctl.c              | 5 +----
 35 files changed, 20 insertions(+), 81 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 552719c3bbc3..b0327402b3e6 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -3728,7 +3728,7 @@ static int neigh_proc_base_reachable_time(struct ctl_table *ctl, int write,
 
 static struct neigh_sysctl_table {
 	struct ctl_table_header *sysctl_header;
-	struct ctl_table neigh_vars[NEIGH_VAR_MAX + 1];
+	struct ctl_table neigh_vars[NEIGH_VAR_MAX];
 } neigh_sysctl_template __read_mostly = {
 	.neigh_vars = {
 		NEIGH_SYSCTL_ZERO_INTMAX_ENTRY(MCAST_PROBES, "mcast_solicit"),
@@ -3779,7 +3779,6 @@ static struct neigh_sysctl_table {
 			.extra2		= SYSCTL_INT_MAX,
 			.proc_handler	= proc_dointvec_minmax,
 		},
-		{},
 	},
 };
 
@@ -3807,8 +3806,6 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 	if (dev) {
 		dev_name_source = dev->name;
 		/* Terminate the table early */
-		memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
-		       sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
 		neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS + 1;
 	} else {
 		struct neigh_table *tbl = p->tbl;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 6973dda3abda..46f5143e86be 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -660,7 +660,6 @@ static struct ctl_table net_core_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
 	},
-	{ }
 };
 
 static struct ctl_table netns_core_table[] = {
@@ -697,7 +696,6 @@ static struct ctl_table netns_core_table[] = {
 		.extra2		= SYSCTL_ONE,
 		.proc_handler	= proc_dou8vec_minmax,
 	},
-	{ }
 };
 
 static int __init fb_tunnels_only_for_init_net_sysctl_setup(char *str)
@@ -715,7 +713,8 @@ __setup("fb_tunnels=", fb_tunnels_only_for_init_net_sysctl_setup);
 
 static __net_init int sysctl_core_net_init(struct net *net)
 {
-	struct ctl_table *tbl, *tmp;
+	struct ctl_table *tbl;
+	size_t table_size = ARRAY_SIZE(netns_core_table);
 
 	tbl = netns_core_table;
 	if (!net_eq(net, &init_net)) {
@@ -723,8 +722,8 @@ static __net_init int sysctl_core_net_init(struct net *net)
 		if (tbl == NULL)
 			goto err_dup;
 
-		for (tmp = tbl; tmp->procname; tmp++)
-			tmp->data += (char *)net - (char *)&init_net;
+		for (int i = 0; i < table_size; ++i)
+			(tbl + i)->data += (char *)net - (char *)&init_net;
 	}
 
 	net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl,
diff --git a/net/dccp/sysctl.c b/net/dccp/sysctl.c
index ee8d4f5afa72..3fc474d6e57d 100644
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -90,8 +90,6 @@ static struct ctl_table dccp_default_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_ms_jiffies,
 	},
-
-	{ }
 };
 
 static struct ctl_table_header *dccp_table_header;
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index 6dd960ec558c..09b18ee6df00 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -338,7 +338,6 @@ static struct ctl_table lowpan_frags_ns_ctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 /* secret interval has been deprecated */
@@ -351,7 +350,6 @@ static struct ctl_table lowpan_frags_ctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
@@ -370,10 +368,8 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
 			goto err_alloc;
 
 		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns) {
-			table[0].procname = NULL;
+		if (net->user_ns != &init_user_ns)
 			table_size = 0;
-		}
 	}
 
 	table[0].data	= &ieee802154_lowpan->fqdir->high_thresh;
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 7a437f0d4190..6195cc5be1fc 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2515,7 +2515,7 @@ static int ipv4_doint_and_flush(struct ctl_table *ctl, int write,
 
 static struct devinet_sysctl_table {
 	struct ctl_table_header *sysctl_header;
-	struct ctl_table devinet_vars[__IPV4_DEVCONF_MAX];
+	struct ctl_table devinet_vars[IPV4_DEVCONF_MAX];
 } devinet_sysctl = {
 	.devinet_vars = {
 		DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
@@ -2578,7 +2578,7 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name,
 	if (!t)
 		goto out;
 
-	for (i = 0; i < ARRAY_SIZE(t->devinet_vars) - 1; i++) {
+	for (i = 0; i < ARRAY_SIZE(t->devinet_vars); i++) {
 		t->devinet_vars[i].data += (char *)p - (char *)&ipv4_devconf;
 		t->devinet_vars[i].extra1 = p;
 		t->devinet_vars[i].extra2 = net;
@@ -2652,7 +2652,6 @@ static struct ctl_table ctl_forward_entry[] = {
 		.extra1		= &ipv4_devconf,
 		.extra2		= &init_net,
 	},
-	{ },
 };
 #endif
 
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index a4941f53b523..e308779ed77b 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -580,7 +580,6 @@ static struct ctl_table ip4_frags_ns_ctl_table[] = {
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= &dist_min,
 	},
-	{ }
 };
 
 /* secret interval has been deprecated */
@@ -593,7 +592,6 @@ static struct ctl_table ip4_frags_ctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 static int __net_init ip4_frags_ns_ctl_register(struct net *net)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c8f76f56dc16..deecfc0e5a91 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3509,7 +3509,6 @@ static struct ctl_table ipv4_route_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ }
 };
 
 static const char ipv4_route_flush_procname[] = "flush";
@@ -3543,7 +3542,6 @@ static struct ctl_table ipv4_route_netns_table[] = {
 		.mode       = 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ },
 };
 
 static __net_init int sysctl_route_net_init(struct net *net)
@@ -3561,16 +3559,14 @@ static __net_init int sysctl_route_net_init(struct net *net)
 
 		/* Don't export non-whitelisted sysctls to unprivileged users */
 		if (net->user_ns != &init_user_ns) {
-			if (tbl[0].procname != ipv4_route_flush_procname) {
-				tbl[0].procname = NULL;
+			if (tbl[0].procname != ipv4_route_flush_procname)
 				table_size = 0;
-			}
 		}
 
 		/* Update the variables to point into the current struct net
 		 * except for the first element flush
 		 */
-		for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
+		for (i = 1; i < table_size; i++)
 			tbl[i].data += (void *)net - (void *)&init_net;
 	}
 	tbl[0].extra1 = net;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 7e4f16a7dcc1..c8dae8fc682a 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -575,7 +575,6 @@ static struct ctl_table ipv4_table[] = {
 		.extra1		= &sysctl_fib_sync_mem_min,
 		.extra2		= &sysctl_fib_sync_mem_max,
 	},
-	{ }
 };
 
 static struct ctl_table ipv4_net_table[] = {
@@ -1502,12 +1501,12 @@ static struct ctl_table ipv4_net_table[] = {
 		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ONE,
 	},
-	{ }
 };
 
 static __net_init int ipv4_sysctl_init_net(struct net *net)
 {
 	struct ctl_table *table;
+	size_t table_size = ARRAY_SIZE(ipv4_net_table);
 
 	table = ipv4_net_table;
 	if (!net_eq(net, &init_net)) {
@@ -1517,7 +1516,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 		if (!table)
 			goto err_alloc;
 
-		for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) {
+		for (i = 0; i < table_size; i++) {
 			if (table[i].data) {
 				/* Update the variables to point into
 				 * the current struct net
@@ -1533,7 +1532,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 	}
 
 	net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
-						    ARRAY_SIZE(ipv4_net_table));
+						    table_size);
 	if (!net->ipv4.ipv4_hdr)
 		goto err_reg;
 
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index c33bca2c3841..4c74fec034c5 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -152,7 +152,6 @@ static struct ctl_table xfrm4_policy_table[] = {
 		.mode           = 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ }
 };
 
 static __net_init int xfrm4_net_sysctl_init(struct net *net)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 247bd4d8ee45..69619a52d4f8 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7181,9 +7181,6 @@ static const struct ctl_table addrconf_sysctl[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_TWO,
 	},
-	{
-		/* sentinel */
-	}
 };
 
 static int __addrconf_sysctl_register(struct net *net, char *dev_name,
@@ -7197,7 +7194,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
 	if (!table)
 		goto out;
 
-	for (i = 0; table[i].data; i++) {
+	for (i = 0; i < ARRAY_SIZE(addrconf_sysctl); i++) {
 		table[i].data += (char *)p - (char *)&ipv6_devconf;
 		/* If one of these is already set, then it is not safe to
 		 * overwrite either of them: this makes proc_dointvec_minmax
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 1635da07285f..91cbf8e8009f 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -1206,7 +1206,6 @@ static struct ctl_table ipv6_icmp_table_template[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
-	{ },
 };
 
 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index acb4f119e11f..afb343cb77ac 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -436,7 +436,6 @@ static struct ctl_table ip6_frags_ns_ctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 /* secret interval has been deprecated */
@@ -449,7 +448,6 @@ static struct ctl_table ip6_frags_ctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1f4b935a0e57..b49137c3031b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6428,7 +6428,6 @@ static struct ctl_table ipv6_route_table_template[] = {
 		.extra1		=	SYSCTL_ZERO,
 		.extra2		=	SYSCTL_ONE,
 	},
-	{ }
 };
 
 struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
@@ -6452,10 +6451,6 @@ struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
 		table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
 		table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
 		table[10].data = &net->ipv6.sysctl.skip_notify_on_dev_down;
-
-		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns)
-			table[1].procname = NULL;
 	}
 
 	return table;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 888676163e90..9f40bb12fbdd 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -213,7 +213,6 @@ static struct ctl_table ipv6_table_template[] = {
 		.proc_handler	= proc_doulongvec_minmax,
 		.extra2		= &ioam6_id_wide_max,
 	},
-	{ }
 };
 
 static struct ctl_table ipv6_rotable[] = {
@@ -248,7 +247,6 @@ static struct ctl_table ipv6_rotable[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif /* CONFIG_NETLABEL */
-	{ }
 };
 
 static int __net_init ipv6_sysctl_net_init(struct net *net)
@@ -264,7 +262,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 	if (!ipv6_table)
 		goto out;
 	/* Update the variables to point into the current struct net */
-	for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
+	for (i = 0; i < ARRAY_SIZE(ipv6_table_template); i++)
 		ipv6_table[i].data += (void *)net - (void *)&init_net;
 
 	ipv6_route_table = ipv6_route_sysctl_init(net);
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 42fb6996b077..499b5f5c19fc 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -184,7 +184,6 @@ static struct ctl_table xfrm6_policy_table[] = {
 		.mode		= 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ }
 };
 
 static int __net_init xfrm6_net_sysctl_init(struct net *net)
diff --git a/net/llc/sysctl_net_llc.c b/net/llc/sysctl_net_llc.c
index 8443a6d841b0..72e101135f8c 100644
--- a/net/llc/sysctl_net_llc.c
+++ b/net/llc/sysctl_net_llc.c
@@ -44,11 +44,6 @@ static struct ctl_table llc2_timeout_table[] = {
 		.mode		= 0644,
 		.proc_handler   = proc_dointvec_jiffies,
 	},
-	{ },
-};
-
-static struct ctl_table llc_station_table[] = {
-	{ },
 };
 
 static struct ctl_table_header *llc2_timeout_header;
@@ -56,8 +51,9 @@ static struct ctl_table_header *llc_station_header;
 
 int __init llc_sysctl_init(void)
 {
+	struct ctl_table empty[1] = {};
 	llc2_timeout_header = register_net_sysctl(&init_net, "net/llc/llc2/timeout", llc2_timeout_table);
-	llc_station_header = register_net_sysctl(&init_net, "net/llc/station", llc_station_table);
+	llc_station_header = register_net_sysctl_sz(&init_net, "net/llc/station", empty, 0);
 
 	if (!llc2_timeout_header || !llc_station_header) {
 		llc_sysctl_exit();
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6dab883a08dd..e163fac55ffa 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1393,7 +1393,6 @@ static const struct ctl_table mpls_dev_table[] = {
 		.proc_handler	= mpls_conf_proc,
 		.data		= MPLS_PERDEV_SYSCTL_OFFSET(input_enabled),
 	},
-	{ }
 };
 
 static int mpls_dev_sysctl_register(struct net_device *dev,
@@ -2689,7 +2688,7 @@ static int mpls_net_init(struct net *net)
 	/* Table data contains only offsets relative to the base of
 	 * the mdev at this point, so make them absolute.
 	 */
-	for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
+	for (i = 0; i < ARRAY_SIZE(mpls_table); i++)
 		table[i].data = (char *)net + (uintptr_t)table[i].data;
 
 	net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 13fe0748dde8..8bf7c26a0878 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -156,7 +156,6 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.mode = 0644,
 		.proc_handler = proc_dointvec_jiffies,
 	},
-	{}
 };
 
 static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
diff --git a/net/netrom/sysctl_net_netrom.c b/net/netrom/sysctl_net_netrom.c
index 79fb2d3f477b..7dc0fa628f2e 100644
--- a/net/netrom/sysctl_net_netrom.c
+++ b/net/netrom/sysctl_net_netrom.c
@@ -140,7 +140,6 @@ static struct ctl_table nr_table[] = {
 		.extra1		= &min_reset,
 		.extra2		= &max_reset
 	},
-	{ }
 };
 
 int __init nr_register_sysctl(void)
diff --git a/net/phonet/sysctl.c b/net/phonet/sysctl.c
index 0d0bf41381c2..82fc22467a09 100644
--- a/net/phonet/sysctl.c
+++ b/net/phonet/sysctl.c
@@ -81,7 +81,6 @@ static struct ctl_table phonet_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_local_port_range,
 	},
-	{ }
 };
 
 int __init phonet_sysctl_init(void)
diff --git a/net/rds/ib_sysctl.c b/net/rds/ib_sysctl.c
index e4e41b3afce7..2af678e71e3c 100644
--- a/net/rds/ib_sysctl.c
+++ b/net/rds/ib_sysctl.c
@@ -103,7 +103,6 @@ static struct ctl_table rds_ib_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ }
 };
 
 void rds_ib_sysctl_exit(void)
diff --git a/net/rds/sysctl.c b/net/rds/sysctl.c
index e381bbcd9cc1..025f518a4349 100644
--- a/net/rds/sysctl.c
+++ b/net/rds/sysctl.c
@@ -89,7 +89,6 @@ static struct ctl_table rds_sysctl_rds_table[] = {
 		.mode           = 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ }
 };
 
 void rds_sysctl_exit(void)
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index 2dba7505b414..d8111ac83bb6 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -86,7 +86,6 @@ static struct ctl_table rds_tcp_sysctl_table[] = {
 		.proc_handler   = rds_tcp_skbuf_handler,
 		.extra1		= &rds_tcp_min_rcvbuf,
 	},
-	{ }
 };
 
 u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
diff --git a/net/rose/sysctl_net_rose.c b/net/rose/sysctl_net_rose.c
index d391d7758f52..d801315b7083 100644
--- a/net/rose/sysctl_net_rose.c
+++ b/net/rose/sysctl_net_rose.c
@@ -112,7 +112,6 @@ static struct ctl_table rose_table[] = {
 		.extra1		= &min_window,
 		.extra2		= &max_window
 	},
-	{ }
 };
 
 void __init rose_register_sysctl(void)
diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c
index c9bedd0e2d86..9bf9a1f6e4cb 100644
--- a/net/rxrpc/sysctl.c
+++ b/net/rxrpc/sysctl.c
@@ -127,7 +127,6 @@ static struct ctl_table rxrpc_sysctl_table[] = {
 		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&four,
 	},
-	{ }
 };
 
 int __init rxrpc_sysctl_init(void)
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index f65d6f92afcb..6894072af210 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -80,8 +80,6 @@ static struct ctl_table sctp_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-
-	{ /* sentinel */ }
 };
 
 /* The following index defines are used in sctp_sysctl_net_register().
@@ -384,8 +382,6 @@ static struct ctl_table sctp_net_table[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &pf_expose_max,
 	},
-
-	{ /* sentinel */ }
 };
 
 static int proc_sctp_do_hmac_alg(struct ctl_table *ctl, int write,
@@ -604,7 +600,7 @@ int sctp_sysctl_net_register(struct net *net)
 	if (!table)
 		return -ENOMEM;
 
-	for (i = 0; table[i].data; i++)
+	for (i = 0; i < ARRAY_SIZE(sctp_net_table); i++)
 		table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
 
 	table[SCTP_RTO_MIN_IDX].extra2 = &net->sctp.rto_max;
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index a5946d1b9d60..bd0b7e2f8824 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -90,7 +90,6 @@ static struct ctl_table smc_table[] = {
 		.extra1		= &conns_per_lgr_min,
 		.extra2		= &conns_per_lgr_max,
 	},
-	{  }
 };
 
 int __net_init smc_sysctl_net_init(struct net *net)
diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 93941ab12549..5f3170a1c9bb 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -160,7 +160,6 @@ static struct ctl_table debug_table[] = {
 		.mode		= 0444,
 		.proc_handler	= proc_do_xprt,
 	},
-	{ }
 };
 
 void
diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
index f86970733eb0..474f7a98fe9e 100644
--- a/net/sunrpc/xprtrdma/svc_rdma.c
+++ b/net/sunrpc/xprtrdma/svc_rdma.c
@@ -209,7 +209,6 @@ static struct ctl_table svcrdma_parm_table[] = {
 		.extra1		= &zero,
 		.extra2		= &zero,
 	},
-	{ },
 };
 
 static void svc_rdma_proc_cleanup(void)
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 29b0562d62e7..9a8ce5df83ca 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -137,7 +137,6 @@ static struct ctl_table xr_tunables_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ },
 };
 
 #endif
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index bb9b747d58a1..f62f7b65455b 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -160,7 +160,6 @@ static struct ctl_table xs_tunables_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ },
 };
 
 /*
diff --git a/net/tipc/sysctl.c b/net/tipc/sysctl.c
index 9fb65c988f7f..30d2e06e3d8c 100644
--- a/net/tipc/sysctl.c
+++ b/net/tipc/sysctl.c
@@ -91,7 +91,6 @@ static struct ctl_table tipc_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
 	},
-	{}
 };
 
 int tipc_register_sysctl(void)
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
index 3e84b31c355a..ae45d4cfac39 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -19,7 +19,6 @@ static struct ctl_table unix_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{ }
 };
 
 int __net_init unix_sysctl_register(struct net *net)
diff --git a/net/x25/sysctl_net_x25.c b/net/x25/sysctl_net_x25.c
index e9802afa43d0..643f50874dfe 100644
--- a/net/x25/sysctl_net_x25.c
+++ b/net/x25/sysctl_net_x25.c
@@ -71,7 +71,6 @@ static struct ctl_table x25_table[] = {
 		.mode = 	0644,
 		.proc_handler = proc_dointvec,
 	},
-	{ },
 };
 
 int __init x25_register_sysctl(void)
diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
index 7fdeafc838a7..b0f542805e6e 100644
--- a/net/xfrm/xfrm_sysctl.c
+++ b/net/xfrm/xfrm_sysctl.c
@@ -38,7 +38,6 @@ static struct ctl_table xfrm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{}
 };
 
 int __net_init xfrm_sysctl_init(struct net *net)
@@ -57,10 +56,8 @@ int __net_init xfrm_sysctl_init(struct net *net)
 	table[3].data = &net->xfrm.sysctl_acq_expires;
 
 	/* Don't export sysctls to unprivileged users */
-	if (net->user_ns != &init_user_ns) {
-		table[0].procname = NULL;
+	if (net->user_ns != &init_user_ns)
 		table_size = 0;
-	}
 
 	net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
 						      table_size);

-- 
2.43.0
[PATCH v2 2/4] netfilter: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados via B4 Relay 1 month ago
From: Joel Granados <j.granados@samsung.com>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which will
reduce the overall build time size of the kernel and run time memory
bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

* Remove sentinel elements from ctl_table structs
* Remove instances where an array element is zeroed out to make it look
  like a sentinel. This is not longer needed and is safe after commit
  c899710fe7f9 ("networking: Update to register_net_sysctl_sz") added
  the array size to the ctl_table registration
* Remove the need for having __NF_SYSCTL_CT_LAST_SYSCTL as the
  sysctl array size is now in NF_SYSCTL_CT_LAST_SYSCTL
* Remove extra element in ctl_table arrays declarations

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 net/bridge/br_netfilter_hooks.c         | 1 -
 net/ipv6/netfilter/nf_conntrack_reasm.c | 1 -
 net/netfilter/ipvs/ip_vs_ctl.c          | 5 +----
 net/netfilter/ipvs/ip_vs_lblc.c         | 5 +----
 net/netfilter/ipvs/ip_vs_lblcr.c        | 5 +----
 net/netfilter/nf_conntrack_standalone.c | 6 +-----
 net/netfilter/nf_log.c                  | 3 +--
 7 files changed, 5 insertions(+), 21 deletions(-)

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 35e10c5a766d..d31f57ffe985 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -1219,7 +1219,6 @@ static struct ctl_table brnf_table[] = {
 		.mode		= 0644,
 		.proc_handler	= brnf_sysctl_call_tables,
 	},
-	{ }
 };
 
 static inline void br_netfilter_sysctl_default(struct brnf_net *brnf)
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 1a51a44571c3..8531750ec081 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -62,7 +62,6 @@ static struct ctl_table nf_ct_frag6_sysctl_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
 	},
-	{ }
 };
 
 static int nf_ct_frag6_sysctl_register(struct net *net)
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 143a341bbc0a..50b5dbe40eb8 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2263,7 +2263,6 @@ static struct ctl_table vs_vars[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-	{ }
 };
 
 #endif
@@ -4286,10 +4285,8 @@ static int __net_init ip_vs_control_net_init_sysctl(struct netns_ipvs *ipvs)
 			return -ENOMEM;
 
 		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns) {
-			tbl[0].procname = NULL;
+		if (net->user_ns != &init_user_ns)
 			ctl_table_size = 0;
-		}
 	} else
 		tbl = vs_vars;
 	/* Initialize sysctl defaults */
diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c
index 8ceec7a2fa8f..2423513d701d 100644
--- a/net/netfilter/ipvs/ip_vs_lblc.c
+++ b/net/netfilter/ipvs/ip_vs_lblc.c
@@ -123,7 +123,6 @@ static struct ctl_table vs_vars_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 #endif
 
@@ -563,10 +562,8 @@ static int __net_init __ip_vs_lblc_init(struct net *net)
 			return -ENOMEM;
 
 		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns) {
-			ipvs->lblc_ctl_table[0].procname = NULL;
+		if (net->user_ns != &init_user_ns)
 			vars_table_size = 0;
-		}
 
 	} else
 		ipvs->lblc_ctl_table = vs_vars_table;
diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c
index 0fb64707213f..cdb1d4bf6761 100644
--- a/net/netfilter/ipvs/ip_vs_lblcr.c
+++ b/net/netfilter/ipvs/ip_vs_lblcr.c
@@ -294,7 +294,6 @@ static struct ctl_table vs_vars_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 #endif
 
@@ -749,10 +748,8 @@ static int __net_init __ip_vs_lblcr_init(struct net *net)
 			return -ENOMEM;
 
 		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns) {
-			ipvs->lblcr_ctl_table[0].procname = NULL;
+		if (net->user_ns != &init_user_ns)
 			vars_table_size = 0;
-		}
 	} else
 		ipvs->lblcr_ctl_table = vs_vars_table;
 	ipvs->sysctl_lblcr_expiration = DEFAULT_EXPIRATION;
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 0ee98ce5b816..2f226cfb32d0 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -616,11 +616,9 @@ enum nf_ct_sysctl_index {
 	NF_SYSCTL_CT_LWTUNNEL,
 #endif
 
-	__NF_SYSCTL_CT_LAST_SYSCTL,
+	NF_SYSCTL_CT_LAST_SYSCTL,
 };
 
-#define NF_SYSCTL_CT_LAST_SYSCTL (__NF_SYSCTL_CT_LAST_SYSCTL + 1)
-
 static struct ctl_table nf_ct_sysctl_table[] = {
 	[NF_SYSCTL_CT_MAX] = {
 		.procname	= "nf_conntrack_max",
@@ -957,7 +955,6 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 		.proc_handler	= nf_hooks_lwtunnel_sysctl_handler,
 	},
 #endif
-	{}
 };
 
 static struct ctl_table nf_ct_netfilter_table[] = {
@@ -968,7 +965,6 @@ static struct ctl_table nf_ct_netfilter_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ }
 };
 
 static void nf_conntrack_standalone_init_tcp_sysctl(struct net *net,
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 370f8231385c..d42ba733496b 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -395,7 +395,7 @@ static const struct seq_operations nflog_seq_ops = {
 
 #ifdef CONFIG_SYSCTL
 static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
-static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
+static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO];
 static struct ctl_table_header *nf_log_sysctl_fhdr;
 
 static struct ctl_table nf_log_sysctl_ftable[] = {
@@ -406,7 +406,6 @@ static struct ctl_table nf_log_sysctl_ftable[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ }
 };
 
 static int nf_log_proc_dostring(struct ctl_table *table, int write,

-- 
2.43.0
[PATCH v2 3/4] appletalk: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados via B4 Relay 1 month ago
From: Joel Granados <j.granados@samsung.com>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which will
reduce the overall build time size of the kernel and run time memory
bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel from atalk_table ctl_table array.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 net/appletalk/sysctl_net_atalk.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/appletalk/sysctl_net_atalk.c b/net/appletalk/sysctl_net_atalk.c
index d945b7c0176d..7aebfe903242 100644
--- a/net/appletalk/sysctl_net_atalk.c
+++ b/net/appletalk/sysctl_net_atalk.c
@@ -40,7 +40,6 @@ static struct ctl_table atalk_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ },
 };
 
 static struct ctl_table_header *atalk_table_header;

-- 
2.43.0
[PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados via B4 Relay 1 month ago
From: Joel Granados <j.granados@samsung.com>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which will
reduce the overall build time size of the kernel and run time memory
bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

When we remove the sentinel from ax25_param_table a buffer overflow
shows its ugly head. The sentinel's data element used to be changed when
CONFIG_AX25_DAMA_SLAVE was not defined. This did not have any adverse
effects as we still stopped on the sentinel because of its null
procname. But now that we do not have the sentinel element, we are
careful to check ax25_param_table's size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
 net/ax25/sysctl_net_ax25.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
index db66e11e7fe8..e55be8817a1e 100644
--- a/net/ax25/sysctl_net_ax25.c
+++ b/net/ax25/sysctl_net_ax25.c
@@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
 		.extra2		= &max_ds_timeout
 	},
 #endif
-
-	{ }	/* that's all, folks! */
 };
 
 int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
@@ -155,7 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
 	if (!table)
 		return -ENOMEM;
 
-	for (k = 0; k < AX25_MAX_VALUES; k++)
+	for (k = 0; k < AX25_MAX_VALUES && k < ARRAY_SIZE(ax25_param_table); k++)
 		table[k].data = &ax25_dev->values[k];
 
 	snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name);

-- 
2.43.0
[PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Kuniyuki Iwashima 1 month ago
From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
Date: Thu, 28 Mar 2024 16:40:05 +0100
> This commit comes at the tail end of a greater effort to remove the
> empty elements at the end of the ctl_table arrays (sentinels) which will
> reduce the overall build time size of the kernel and run time memory
> bloat by ~64 bytes per sentinel (further information Link :
> https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> 
> When we remove the sentinel from ax25_param_table a buffer overflow
> shows its ugly head. The sentinel's data element used to be changed when
> CONFIG_AX25_DAMA_SLAVE was not defined.

I think it's better to define the relation explicitly between the
enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()

  BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));

and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
as done for other enum.


> This did not have any adverse
> effects as we still stopped on the sentinel because of its null
> procname. But now that we do not have the sentinel element, we are
> careful to check ax25_param_table's size.
> 
> Signed-off-by: Joel Granados <j.granados@samsung.com>
> ---
>  net/ax25/sysctl_net_ax25.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
> index db66e11e7fe8..e55be8817a1e 100644
> --- a/net/ax25/sysctl_net_ax25.c
> +++ b/net/ax25/sysctl_net_ax25.c
> @@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
>  		.extra2		= &max_ds_timeout
>  	},
>  #endif
> -
> -	{ }	/* that's all, folks! */
>  };
>  
>  int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> @@ -155,7 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
>  	if (!table)
>  		return -ENOMEM;
>  
> -	for (k = 0; k < AX25_MAX_VALUES; k++)
> +	for (k = 0; k < AX25_MAX_VALUES && k < ARRAY_SIZE(ax25_param_table); k++)
>  		table[k].data = &ax25_dev->values[k];
>  
>  	snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name);
> 
> -- 
> 2.43.0
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados 3 weeks, 2 days ago
On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> Date: Thu, 28 Mar 2024 16:40:05 +0100
> > This commit comes at the tail end of a greater effort to remove the
> > empty elements at the end of the ctl_table arrays (sentinels) which will
> > reduce the overall build time size of the kernel and run time memory
> > bloat by ~64 bytes per sentinel (further information Link :
> > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > 
> > When we remove the sentinel from ax25_param_table a buffer overflow
> > shows its ugly head. The sentinel's data element used to be changed when
> > CONFIG_AX25_DAMA_SLAVE was not defined.
> 
> I think it's better to define the relation explicitly between the
> enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> 
>   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> 
> and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> as done for other enum.

When I remove AX25_VALUES_DS_TIMEOUT from the un-guarded build it
complains in net/ax25/ax25_ds_timer.c (ax25_ds_set_timer). Here is the
report https://lore.kernel.org/oe-kbuild-all/202404040301.qzKmVQGB-lkp@intel.com/.

How best to address this? Should we just guard the whole function and do
nothing when not set? like this:

```
void ax25_ds_set_timer(ax25_dev *ax25_dev)
{
#ifdef COFNIG_AX25_DAMA_SLAVE
        if (ax25_dev == NULL)        ···/* paranoia */
                return;

        ax25_dev->dama.slave_timeout =
                msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
        mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
#else
        return;
#endif
}

```

I'm not too familiar with this, so pointing me to the "correct" way to
handle this would be helpfull.

Thx in advance.

Best

-- 

Joel Granados
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Kuniyuki Iwashima 3 weeks, 2 days ago
From: Joel Granados <j.granados@samsung.com>
Date: Fri, 5 Apr 2024 09:15:31 +0200
> On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> > From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> > Date: Thu, 28 Mar 2024 16:40:05 +0100
> > > This commit comes at the tail end of a greater effort to remove the
> > > empty elements at the end of the ctl_table arrays (sentinels) which will
> > > reduce the overall build time size of the kernel and run time memory
> > > bloat by ~64 bytes per sentinel (further information Link :
> > > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > > 
> > > When we remove the sentinel from ax25_param_table a buffer overflow
> > > shows its ugly head. The sentinel's data element used to be changed when
> > > CONFIG_AX25_DAMA_SLAVE was not defined.
> > 
> > I think it's better to define the relation explicitly between the
> > enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> > 
> >   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> > 
> > and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> > as done for other enum.
> 
> When I remove AX25_VALUES_DS_TIMEOUT from the un-guarded build it
> complains in net/ax25/ax25_ds_timer.c (ax25_ds_set_timer). Here is the
> report https://lore.kernel.org/oe-kbuild-all/202404040301.qzKmVQGB-lkp@intel.com/.
> 
> How best to address this? Should we just guard the whole function and do
> nothing when not set? like this:

It seems fine to me.

ax25_ds_timeout() checks !ax25_dev->dama.slave_timeout, but it's
initialised by kzalloc() during dev setup, so it will be a noop.


> 
> ```
> void ax25_ds_set_timer(ax25_dev *ax25_dev)
> {
> #ifdef COFNIG_AX25_DAMA_SLAVE
>         if (ax25_dev == NULL)        ···/* paranoia */
>                 return;
> 
>         ax25_dev->dama.slave_timeout =
>                 msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
>         mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
> #else
>         return;
> #endif
> }
> 
> ```
> 
> I'm not too familiar with this, so pointing me to the "correct" way to
> handle this would be helpfull.

Also, you will need to guard another use of AX25_VALUES_DS_TIMEOUT in
ax25_dev_device_up().

Thanks!
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados 2 weeks, 2 days ago
On Fri, Apr 05, 2024 at 03:26:58PM -0700, Kuniyuki Iwashima wrote:
> From: Joel Granados <j.granados@samsung.com>
> Date: Fri, 5 Apr 2024 09:15:31 +0200
> > On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> > > From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> > > Date: Thu, 28 Mar 2024 16:40:05 +0100
> > > > This commit comes at the tail end of a greater effort to remove the
> > > > empty elements at the end of the ctl_table arrays (sentinels) which will
> > > > reduce the overall build time size of the kernel and run time memory
> > > > bloat by ~64 bytes per sentinel (further information Link :
> > > > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > > > 
> > > > When we remove the sentinel from ax25_param_table a buffer overflow
> > > > shows its ugly head. The sentinel's data element used to be changed when
> > > > CONFIG_AX25_DAMA_SLAVE was not defined.
> > > 
> > > I think it's better to define the relation explicitly between the
> > > enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> > > 
> > >   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> > > 
> > > and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> > > as done for other enum.
> > 
> > When I remove AX25_VALUES_DS_TIMEOUT from the un-guarded build it
> > complains in net/ax25/ax25_ds_timer.c (ax25_ds_set_timer). Here is the
> > report https://lore.kernel.org/oe-kbuild-all/202404040301.qzKmVQGB-lkp@intel.com/.
> > 
> > How best to address this? Should we just guard the whole function and do
> > nothing when not set? like this:
> 
> It seems fine to me.
> 
> ax25_ds_timeout() checks !ax25_dev->dama.slave_timeout, but it's
> initialised by kzalloc() during dev setup, so it will be a noop.

Just sent v3 with this change.


-- 

Joel Granados
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados 2 weeks, 6 days ago
On Fri, Apr 05, 2024 at 03:26:58PM -0700, Kuniyuki Iwashima wrote:
> From: Joel Granados <j.granados@samsung.com>
> Date: Fri, 5 Apr 2024 09:15:31 +0200
> > On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> > > From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> > > Date: Thu, 28 Mar 2024 16:40:05 +0100
> > > > This commit comes at the tail end of a greater effort to remove the
> > > > empty elements at the end of the ctl_table arrays (sentinels) which will
> > > > reduce the overall build time size of the kernel and run time memory
> > > > bloat by ~64 bytes per sentinel (further information Link :
> > > > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > > > 
> > > > When we remove the sentinel from ax25_param_table a buffer overflow
> > > > shows its ugly head. The sentinel's data element used to be changed when
> > > > CONFIG_AX25_DAMA_SLAVE was not defined.
> > > 
> > > I think it's better to define the relation explicitly between the
> > > enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> > > 
> > >   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> > > 
> > > and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> > > as done for other enum.
> > 
> > When I remove AX25_VALUES_DS_TIMEOUT from the un-guarded build it
> > complains in net/ax25/ax25_ds_timer.c (ax25_ds_set_timer). Here is the
> > report https://lore.kernel.org/oe-kbuild-all/202404040301.qzKmVQGB-lkp@intel.com/.
> > 
> > How best to address this? Should we just guard the whole function and do
> > nothing when not set? like this:
> 
> It seems fine to me.
> 
> ax25_ds_timeout() checks !ax25_dev->dama.slave_timeout, but it's
> initialised by kzalloc() during dev setup, so it will be a noop.
thx. I'll solve it like this then

> 
> 
> > 
> > ```
> > void ax25_ds_set_timer(ax25_dev *ax25_dev)
> > {
> > #ifdef COFNIG_AX25_DAMA_SLAVE
> >         if (ax25_dev == NULL)        ···/* paranoia */
> >                 return;
> > 
> >         ax25_dev->dama.slave_timeout =
> >                 msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
> >         mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
> > #else
> >         return;
> > #endif
> > }
> > 
> > ```
> > 
> > I'm not too familiar with this, so pointing me to the "correct" way to
> > handle this would be helpfull.
> 
> Also, you will need to guard another use of AX25_VALUES_DS_TIMEOUT in
> ax25_dev_device_up().
Yes. I had noticed this already. This was a trivial one though, so I did
not ask about it.

Thx.

Best

-- 

Joel Granados
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados 3 weeks, 4 days ago
On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> Date: Thu, 28 Mar 2024 16:40:05 +0100
> > This commit comes at the tail end of a greater effort to remove the
> > empty elements at the end of the ctl_table arrays (sentinels) which will
> > reduce the overall build time size of the kernel and run time memory
> > bloat by ~64 bytes per sentinel (further information Link :
> > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > 
> > When we remove the sentinel from ax25_param_table a buffer overflow
> > shows its ugly head. The sentinel's data element used to be changed when
> > CONFIG_AX25_DAMA_SLAVE was not defined.
> 
> I think it's better to define the relation explicitly between the
> enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> 
>   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> 
> and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> as done for other enum.
This is a great idea. I'll also try to look and see where else I can add
the explicit relation check.

Thx for the review

> 
> 
> > This did not have any adverse
> > effects as we still stopped on the sentinel because of its null
> > procname. But now that we do not have the sentinel element, we are
> > careful to check ax25_param_table's size.
> > 
> > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > ---
> >  net/ax25/sysctl_net_ax25.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
> > index db66e11e7fe8..e55be8817a1e 100644
> > --- a/net/ax25/sysctl_net_ax25.c
> > +++ b/net/ax25/sysctl_net_ax25.c
> > @@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
> >  		.extra2		= &max_ds_timeout
> >  	},
> >  #endif
> > -
> > -	{ }	/* that's all, folks! */
> >  };
> >  
> >  int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> > @@ -155,7 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> >  	if (!table)
> >  		return -ENOMEM;
> >  
> > -	for (k = 0; k < AX25_MAX_VALUES; k++)
> > +	for (k = 0; k < AX25_MAX_VALUES && k < ARRAY_SIZE(ax25_param_table); k++)
> >  		table[k].data = &ax25_dev->values[k];
> >  
> >  	snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name);
> > 
> > -- 
> > 2.43.0

-- 

Joel Granados
Re: [PATCH v2 4/4] ax.25: Remove the now superfluous sentinel elements from ctl_table array
Posted by Joel Granados 3 weeks, 4 days ago
On Wed, Apr 03, 2024 at 11:16:25AM +0200, Joel Granados wrote:
> On Thu, Mar 28, 2024 at 12:49:34PM -0700, Kuniyuki Iwashima wrote:
> > From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@kernel.org>
> > Date: Thu, 28 Mar 2024 16:40:05 +0100
> > > This commit comes at the tail end of a greater effort to remove the
> > > empty elements at the end of the ctl_table arrays (sentinels) which will
> > > reduce the overall build time size of the kernel and run time memory
> > > bloat by ~64 bytes per sentinel (further information Link :
> > > https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)
> > > 
> > > When we remove the sentinel from ax25_param_table a buffer overflow
> > > shows its ugly head. The sentinel's data element used to be changed when
> > > CONFIG_AX25_DAMA_SLAVE was not defined.
> > 
> > I think it's better to define the relation explicitly between the
> > enum and sysctl table by BUILD_BUG_ON() in ax25_register_dev_sysctl()
> > 
> >   BUILD_BUG_ON(AX25_MAX_VALUES != ARRAY_SIZE(ax25_param_table));
> > 
> > and guard AX25_VALUES_DS_TIMEOUT with #ifdef CONFIG_AX25_DAMA_SLAVE
> > as done for other enum.
> This is a great idea. I'll also try to look and see where else I can add
> the explicit relation check.
> 
> Thx for the review
> 
> > 
> > 
> > > This did not have any adverse
> > > effects as we still stopped on the sentinel because of its null
> > > procname. But now that we do not have the sentinel element, we are
> > > careful to check ax25_param_table's size.
> > > 
> > > Signed-off-by: Joel Granados <j.granados@samsung.com>
> > > ---
> > >  net/ax25/sysctl_net_ax25.c | 4 +---
> > >  1 file changed, 1 insertion(+), 3 deletions(-)
> > > 
> > > diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
> > > index db66e11e7fe8..e55be8817a1e 100644
> > > --- a/net/ax25/sysctl_net_ax25.c
> > > +++ b/net/ax25/sysctl_net_ax25.c
> > > @@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
> > >  		.extra2		= &max_ds_timeout
> > >  	},
> > >  #endif
> > > -
> > > -	{ }	/* that's all, folks! */
> > >  };
> > >  
> > >  int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> > > @@ -155,7 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
> > >  	if (!table)
> > >  		return -ENOMEM;
> > >  
> > > -	for (k = 0; k < AX25_MAX_VALUES; k++)
> > > +	for (k = 0; k < AX25_MAX_VALUES && k < ARRAY_SIZE(ax25_param_table); k++)
And with the BUILD_BUG_ON we don't need to do the `k <
ARRAY_SIZE(ax25_param_table)` any longer. Win/win :)

> > >  		table[k].data = &ax25_dev->values[k];
> > >  
> > >  	snprintf(path, sizeof(path), "net/ax25/%s", ax25_dev->dev->name);
> > > 
> > > -- 
> > > 2.43.0
> 
> -- 
> 
> Joel Granados



-- 

Joel Granados