include/net/tcp.h | 3 ++- net/ipv6/tcp_ipv6.c | 21 ++++++++++++++++----- 2 files changed, 18 insertions(+), 6 deletions(-)
Syzkaller reported this warning:
[ 65.568203][ C0] ------------[ cut here ]------------
[ 65.569339][ C0] WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0
[ 65.575017][ C0] Modules linked in:
[ 65.575699][ C0] CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26
[ 65.577086][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[ 65.577094][ C0] RIP: 0010:inet_sock_destruct+0x1c5/0x1e0
[ 65.577100][ C0] Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b eb 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00
[ 65.577107][ C0] RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206
[ 65.577113][ C0] RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 0000000000000007
[ 65.577117][ C0] RDX: 0000000000000002 RSI: 0000000000000300 RDI: ffff88810b172a00
[ 65.577120][ C0] RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 0000000000100007
[ 65.577123][ C0] R10: 0000000000020000 R11: 0000000000000006 R12: ffff88810b172a00
[ 65.577125][ C0] R13: 0000000000000004 R14: 0000000000000000 R15: ffff888237c31f78
[ 65.577131][ C0] FS: 0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
[ 65.592485][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 65.592489][ C0] CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 00000000000006f0
[ 65.592491][ C0] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 65.592492][ C0] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 65.592495][ C0] Call Trace:
[ 65.596277][ C0] <TASK>
[ 65.598171][ C0] ? __warn+0x88/0x130
[ 65.598874][ C0] ? inet_sock_destruct+0x1c5/0x1e0
[ 65.598879][ C0] ? report_bug+0x18e/0x1a0
[ 65.598883][ C0] ? handle_bug+0x53/0x90
[ 65.598886][ C0] ? exc_invalid_op+0x18/0x70
[ 65.598888][ C0] ? asm_exc_invalid_op+0x1a/0x20
[ 65.598893][ C0] ? inet_sock_destruct+0x1c5/0x1e0
[ 65.598897][ C0] __sk_destruct+0x2a/0x200
[ 65.604664][ C0] rcu_do_batch+0x1aa/0x530
[ 65.605450][ C0] ? rcu_do_batch+0x13b/0x530
[ 65.605456][ C0] rcu_core+0x159/0x2f0
[ 65.605466][ C0] handle_softirqs+0xd3/0x2b0
[ 65.607689][ C0] ? __pfx_smpboot_thread_fn+0x10/0x10
[ 65.607695][ C0] run_ksoftirqd+0x25/0x30
[ 65.607699][ C0] smpboot_thread_fn+0xdd/0x1d0
[ 65.610152][ C0] kthread+0xd3/0x100
[ 65.610158][ C0] ? __pfx_kthread+0x10/0x10
[ 65.610160][ C0] ret_from_fork+0x34/0x50
[ 65.610170][ C0] ? __pfx_kthread+0x10/0x10
[ 65.610172][ C0] ret_from_fork_asm+0x1a/0x30
[ 65.610181][ C0] </TASK>
[ 65.610182][ C0] ---[ end trace 0000000000000000 ]---
Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add()
concurrently when sk->sk_state == TCP_LISTEN with sk->sk_lock unlocked,
which triggers a data-race around sk->sk_forward_alloc:
tcp_v6_rcv
tcp_v6_do_rcv
skb_clone_and_charge_r
sk_rmem_schedule
__sk_mem_schedule
sk_forward_alloc_add()
skb_set_owner_r
sk_mem_charge
sk_forward_alloc_add()
__kfree_skb
skb_release_all
skb_release_head_state
sock_rfree
sk_mem_uncharge
sk_forward_alloc_add()
sk_mem_reclaim
// set local var reclaimable
__sk_mem_reclaim
sk_forward_alloc_add()
In this syzkaller testcase, two threads call tcp_v6_do_rcv() with
skb->truesize=768, the sk_forward_alloc changes like this:
(cpu 1) | (cpu 2) | sk_forward_alloc
... | ... | 0
__sk_mem_schedule() | | +4096 = 4096
| __sk_mem_schedule() | +4096 = 8192
sk_mem_charge() | | -768 = 7424
| sk_mem_charge() | -768 = 6656
... | ... |
sk_mem_uncharge() | | +768 = 7424
reclaimable=7424 | |
| sk_mem_uncharge() | +768 = 8192
| reclaimable=8192 |
__sk_mem_reclaim() | | -4096 = 4096
| __sk_mem_reclaim() | -8192 = -4096 != 0
Add lock around tcp_v6_do_rcv() in tcp_v6_rcv() will have some the
performance impacts, only add lock when opt_skb clone occurs. In some
scenes, tcp_v6_do_rcv() is embraced by sk->sk_lock, add
TCP_SKB_CB(skb)->sk_lock_capability to avoid re-locking.
Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
---
include/net/tcp.h | 3 ++-
net/ipv6/tcp_ipv6.c | 21 ++++++++++++++++-----
2 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d1948d357dad..110a23dda1eb 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -961,7 +961,8 @@ struct tcp_skb_cb {
__u8 txstamp_ack:1, /* Record TX timestamp for ack? */
eor:1, /* Is skb MSG_EOR marked? */
has_rxtstamp:1, /* SKB has a RX timestamp */
- unused:5;
+ sk_lock_capability:1, /* Avoid re-lock flag */
+ unused:4;
__u32 ack_seq; /* Sequence number ACK'd */
union {
struct {
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d71ab4e1efe1..a1166035fbce 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1588,6 +1588,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
struct sk_buff *opt_skb = NULL;
enum skb_drop_reason reason;
struct tcp_sock *tp;
+ bool sk_lock_flag = false;
/* Imagine: socket is IPv6. IPv4 packet arrives,
goes to IPv4 receive handler and backlogged.
@@ -1618,8 +1619,13 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
by tcp. Feel free to propose better solution.
--ANK (980728)
*/
- if (np->rxopt.all)
+ if (np->rxopt.all) {
+ if (TCP_SKB_CB(skb)->sk_lock_capability) {
+ sk_lock_flag = true;
+ bh_lock_sock_nested(sk);
+ }
opt_skb = skb_clone_and_charge_r(skb, sk);
+ }
if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
struct dst_entry *dst;
@@ -1641,7 +1647,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
tcp_rcv_established(sk, skb);
if (opt_skb)
goto ipv6_pktoptions;
- return 0;
+ goto unlock;
}
if (tcp_checksum_complete(skb))
@@ -1658,7 +1664,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
}
if (opt_skb)
__kfree_skb(opt_skb);
- return 0;
+ goto unlock;
}
} else
sock_rps_save_rxhash(sk, skb);
@@ -1668,7 +1674,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
goto reset;
if (opt_skb)
goto ipv6_pktoptions;
- return 0;
+ goto unlock;
reset:
tcp_v6_send_reset(sk, skb, sk_rst_convert_drop_reason(reason));
@@ -1676,7 +1682,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
if (opt_skb)
__kfree_skb(opt_skb);
sk_skb_reason_drop(sk, skb, reason);
- return 0;
+ goto unlock;
csum_err:
reason = SKB_DROP_REASON_TCP_CSUM;
trace_tcp_bad_csum(skb);
@@ -1715,6 +1721,9 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
}
consume_skb(opt_skb);
+unlock:
+ if (sk_lock_flag)
+ bh_unlock_sock(sk);
return 0;
}
@@ -1900,7 +1909,9 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
skb->dev = NULL;
if (sk->sk_state == TCP_LISTEN) {
+ TCP_SKB_CB(skb)->sk_lock_capability = true;
ret = tcp_v6_do_rcv(sk, skb);
+ TCP_SKB_CB(skb)->sk_lock_capability = false;
goto put_and_return;
}
--
2.34.1On Thu, Oct 31, 2024 at 1:06 PM Wang Liang <wangliang74@huawei.com> wrote:
>
> Syzkaller reported this warning:
Was this a public report ?
> [ 65.568203][ C0] ------------[ cut here ]------------
> [ 65.569339][ C0] WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0
> [ 65.575017][ C0] Modules linked in:
> [ 65.575699][ C0] CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26
> [ 65.577086][ C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> [ 65.577094][ C0] RIP: 0010:inet_sock_destruct+0x1c5/0x1e0
> [ 65.577100][ C0] Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b eb 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00
> [ 65.577107][ C0] RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206
> [ 65.577113][ C0] RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 0000000000000007
> [ 65.577117][ C0] RDX: 0000000000000002 RSI: 0000000000000300 RDI: ffff88810b172a00
> [ 65.577120][ C0] RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 0000000000100007
> [ 65.577123][ C0] R10: 0000000000020000 R11: 0000000000000006 R12: ffff88810b172a00
> [ 65.577125][ C0] R13: 0000000000000004 R14: 0000000000000000 R15: ffff888237c31f78
> [ 65.577131][ C0] FS: 0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
> [ 65.592485][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 65.592489][ C0] CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 00000000000006f0
> [ 65.592491][ C0] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 65.592492][ C0] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 65.592495][ C0] Call Trace:
> [ 65.596277][ C0] <TASK>
> [ 65.598171][ C0] ? __warn+0x88/0x130
> [ 65.598874][ C0] ? inet_sock_destruct+0x1c5/0x1e0
> [ 65.598879][ C0] ? report_bug+0x18e/0x1a0
> [ 65.598883][ C0] ? handle_bug+0x53/0x90
> [ 65.598886][ C0] ? exc_invalid_op+0x18/0x70
> [ 65.598888][ C0] ? asm_exc_invalid_op+0x1a/0x20
> [ 65.598893][ C0] ? inet_sock_destruct+0x1c5/0x1e0
> [ 65.598897][ C0] __sk_destruct+0x2a/0x200
> [ 65.604664][ C0] rcu_do_batch+0x1aa/0x530
> [ 65.605450][ C0] ? rcu_do_batch+0x13b/0x530
> [ 65.605456][ C0] rcu_core+0x159/0x2f0
> [ 65.605466][ C0] handle_softirqs+0xd3/0x2b0
> [ 65.607689][ C0] ? __pfx_smpboot_thread_fn+0x10/0x10
> [ 65.607695][ C0] run_ksoftirqd+0x25/0x30
> [ 65.607699][ C0] smpboot_thread_fn+0xdd/0x1d0
> [ 65.610152][ C0] kthread+0xd3/0x100
> [ 65.610158][ C0] ? __pfx_kthread+0x10/0x10
> [ 65.610160][ C0] ret_from_fork+0x34/0x50
> [ 65.610170][ C0] ? __pfx_kthread+0x10/0x10
> [ 65.610172][ C0] ret_from_fork_asm+0x1a/0x30
> [ 65.610181][ C0] </TASK>
> [ 65.610182][ C0] ---[ end trace 0000000000000000 ]---
>
> Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add()
> concurrently when sk->sk_state == TCP_LISTEN with sk->sk_lock unlocked,
> which triggers a data-race around sk->sk_forward_alloc:
> tcp_v6_rcv
> tcp_v6_do_rcv
> skb_clone_and_charge_r
> sk_rmem_schedule
> __sk_mem_schedule
> sk_forward_alloc_add()
> skb_set_owner_r
> sk_mem_charge
> sk_forward_alloc_add()
> __kfree_skb
> skb_release_all
> skb_release_head_state
> sock_rfree
> sk_mem_uncharge
> sk_forward_alloc_add()
> sk_mem_reclaim
> // set local var reclaimable
> __sk_mem_reclaim
> sk_forward_alloc_add()
>
> In this syzkaller testcase, two threads call tcp_v6_do_rcv() with
> skb->truesize=768, the sk_forward_alloc changes like this:
> (cpu 1) | (cpu 2) | sk_forward_alloc
> ... | ... | 0
> __sk_mem_schedule() | | +4096 = 4096
> | __sk_mem_schedule() | +4096 = 8192
> sk_mem_charge() | | -768 = 7424
> | sk_mem_charge() | -768 = 6656
> ... | ... |
> sk_mem_uncharge() | | +768 = 7424
> reclaimable=7424 | |
> | sk_mem_uncharge() | +768 = 8192
> | reclaimable=8192 |
> __sk_mem_reclaim() | | -4096 = 4096
> | __sk_mem_reclaim() | -8192 = -4096 != 0
>
> Add lock around tcp_v6_do_rcv() in tcp_v6_rcv() will have some the
> performance impacts, only add lock when opt_skb clone occurs. In some
> scenes, tcp_v6_do_rcv() is embraced by sk->sk_lock, add
> TCP_SKB_CB(skb)->sk_lock_capability to avoid re-locking.
>
> Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
> Signed-off-by: Wang Liang <wangliang74@huawei.com>
> ---
> include/net/tcp.h | 3 ++-
> net/ipv6/tcp_ipv6.c | 21 ++++++++++++++++-----
> 2 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index d1948d357dad..110a23dda1eb 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -961,7 +961,8 @@ struct tcp_skb_cb {
> __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
> eor:1, /* Is skb MSG_EOR marked? */
> has_rxtstamp:1, /* SKB has a RX timestamp */
> - unused:5;
> + sk_lock_capability:1, /* Avoid re-lock flag */
> + unused:4;
> __u32 ack_seq; /* Sequence number ACK'd */
> union {
> struct {
Oh the horror, this is completely wrong and unsafe anyway.
TCP listen path MUST be lockless, and stay lockless.
Ask yourself : Why would a listener even hold a pktoptions in the first place ?
Normally, each request socket can hold an ireq->pktopts (see in
tcp_v6_init_req())
The skb_clone_and_charge_r() happen later in tcp_v6_syn_recv_sock()
The correct fix is to _not_ call skb_clone_and_charge_r() for a
listener socket, of course, this never made _any_ sense.
The following patch should fix both TCP and DCCP, and as a bonus make
TCP SYN processing faster
for listeners requesting these IPV6_PKTOPTIONS things.
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index da5dba120bc9a55c5fd9d6feda791b0ffc887423..d6649246188d72b3df6c74750779b7aa5910dcb7
100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -618,7 +618,7 @@ static int dccp_v6_do_rcv(struct sock *sk, struct
sk_buff *skb)
by tcp. Feel free to propose better solution.
--ANK (980728)
*/
- if (np->rxopt.all)
+ if (np->rxopt.all && sk->sk_state != DCCP_LISTEN)
opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == DCCP_OPEN) { /* Fast path */
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d71ab4e1efe1c6598cf3d3e4334adf0881064ce9..e643dbaec9ccc92eb2d9103baf185c957ad1dd2e
100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1605,25 +1605,12 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
* is currently called with bh processing disabled.
*/
- /* Do Stevens' IPV6_PKTOPTIONS.
-
- Yes, guys, it is the only place in our code, where we
- may make it not affecting IPv4.
- The rest of code is protocol independent,
- and I do not like idea to uglify IPv4.
-
- Actually, all the idea behind IPV6_PKTOPTIONS
- looks not very well thought. For now we latch
- options, received in the last packet, enqueued
- by tcp. Feel free to propose better solution.
- --ANK (980728)
- */
- if (np->rxopt.all)
- opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
struct dst_entry *dst;
+ if (np->rxopt.all)
+ opt_skb = skb_clone_and_charge_r(skb, sk);
dst = rcu_dereference_protected(sk->sk_rx_dst,
lockdep_sock_is_held(sk));
@@ -1656,13 +1643,13 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
if (reason)
goto reset;
}
- if (opt_skb)
- __kfree_skb(opt_skb);
return 0;
}
} else
sock_rps_save_rxhash(sk, skb);
+ if (np->rxopt.all)
+ opt_skb = skb_clone_and_charge_r(skb, sk);
reason = tcp_rcv_state_process(sk, skb);
if (reason)
goto reset;
在 2024/10/31 22:08, Eric Dumazet 写道:
> On Thu, Oct 31, 2024 at 1:06 PM Wang Liang <wangliang74@huawei.com> wrote:
>> Syzkaller reported this warning:
> Was this a public report ?
Yes，I find the report here (the C repo in the url is useful):
https://syzkaller.appspot.com/bug?id=3e9b62ff331dcc3a6c28c41207f3b9911828a46b
>> [ 65.568203][ C0] ------------[ cut here ]------------
>> [ 65.569339][ C0] WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0
>> [ 65.575017][ C0] Modules linked in:
>> [ 65.575699][ C0] CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26
>> [ ...]
> Oh the horror, this is completely wrong and unsafe anyway.
>
> TCP listen path MUST be lockless, and stay lockless.
>
> Ask yourself : Why would a listener even hold a pktoptions in the first place ?
>
> Normally, each request socket can hold an ireq->pktopts (see in
> tcp_v6_init_req())
>
> The skb_clone_and_charge_r() happen later in tcp_v6_syn_recv_sock()
>
> The correct fix is to _not_ call skb_clone_and_charge_r() for a
> listener socket, of course, this never made _any_ sense.
>
> The following patch should fix both TCP and DCCP, and as a bonus make
> TCP SYN processing faster
> for listeners requesting these IPV6_PKTOPTIONS things.
Thank you very much for your suggestion and patch!
However, the problem remains unsolved when I use the following patch to
test.
Because skb_clone_and_charge_r() is still called when sk_state is
TCP_LISTEN in discard tag.
So I modify the patch like this (it works after local test):
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index da5dba120bc9..2d07f7385783 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -618,7 +618,7 @@ static int dccp_v6_do_rcv(struct sock *sk, struct
sk_buff *skb)
by tcp. Feel free to propose better solution.
--ANK (980728)
*/
- if (np->rxopt.all)
+ if (np->rxopt.all && (sk->sk_state != DCCP_LISTEN))
opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == DCCP_OPEN) { /* Fast path */
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d71ab4e1efe1..0ab06ed78cac 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1618,7 +1618,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff
*skb)
by tcp. Feel free to propose better solution.
--ANK (980728)
*/
- if (np->rxopt.all)
+ if (np->rxopt.all && (sk->sk_state != TCP_LISTEN))
opt_skb = skb_clone_and_charge_r(skb, sk);
if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
@@ -1656,8 +1656,6 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff
*skb)
if (reason)
goto reset;
}
- if (opt_skb)
- __kfree_skb(opt_skb);
return 0;
}
} else
> diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
> index da5dba120bc9a55c5fd9d6feda791b0ffc887423..d6649246188d72b3df6c74750779b7aa5910dcb7
> 100644
> --- a/net/dccp/ipv6.c
> +++ b/net/dccp/ipv6.c
> @@ -618,7 +618,7 @@ static int dccp_v6_do_rcv(struct sock *sk, struct
> sk_buff *skb)
> by tcp. Feel free to propose better solution.
> --ANK (980728)
> */
> - if (np->rxopt.all)
> + if (np->rxopt.all && sk->sk_state != DCCP_LISTEN)
> opt_skb = skb_clone_and_charge_r(skb, sk);
>
> if (sk->sk_state == DCCP_OPEN) { /* Fast path */
> diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
> index d71ab4e1efe1c6598cf3d3e4334adf0881064ce9..e643dbaec9ccc92eb2d9103baf185c957ad1dd2e
> 100644
> --- a/net/ipv6/tcp_ipv6.c
> +++ b/net/ipv6/tcp_ipv6.c
> @@ -1605,25 +1605,12 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
> * is currently called with bh processing disabled.
> */
>
> - /* Do Stevens' IPV6_PKTOPTIONS.
> -
> - Yes, guys, it is the only place in our code, where we
> - may make it not affecting IPv4.
> - The rest of code is protocol independent,
> - and I do not like idea to uglify IPv4.
> -
> - Actually, all the idea behind IPV6_PKTOPTIONS
> - looks not very well thought. For now we latch
> - options, received in the last packet, enqueued
> - by tcp. Feel free to propose better solution.
> - --ANK (980728)
> - */
> - if (np->rxopt.all)
> - opt_skb = skb_clone_and_charge_r(skb, sk);
>
> if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
> struct dst_entry *dst;
>
> + if (np->rxopt.all)
> + opt_skb = skb_clone_and_charge_r(skb, sk);
> dst = rcu_dereference_protected(sk->sk_rx_dst,
> lockdep_sock_is_held(sk));
>
> @@ -1656,13 +1643,13 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
> if (reason)
> goto reset;
> }
> - if (opt_skb)
> - __kfree_skb(opt_skb);
> return 0;
> }
> } else
> sock_rps_save_rxhash(sk, skb);
>
> + if (np->rxopt.all)
> + opt_skb = skb_clone_and_charge_r(skb, sk);
> reason = tcp_rcv_state_process(sk, skb);
> if (reason)
> goto reset;
On Fri, Nov 1, 2024 at 7:24 AM Wang Liang <wangliang74@huawei.com> wrote: > > > 在 2024/10/31 22:08, Eric Dumazet 写道: > > On Thu, Oct 31, 2024 at 1:06 PM Wang Liang <wangliang74@huawei.com> wrote: > >> Syzkaller reported this warning: > > Was this a public report ? > Yes，I find the report here (the C repo in the url is useful): > > https://syzkaller.appspot.com/bug?id=3e9b62ff331dcc3a6c28c41207f3b9911828a46b > >> [ 65.568203][ C0] ------------[ cut here ]------------ > >> [ 65.569339][ C0] WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0 > >> [ 65.575017][ C0] Modules linked in: > >> [ 65.575699][ C0] CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26 > >> [ ...] > > Oh the horror, this is completely wrong and unsafe anyway. > > > > TCP listen path MUST be lockless, and stay lockless. > > > > Ask yourself : Why would a listener even hold a pktoptions in the first place ? > > > > Normally, each request socket can hold an ireq->pktopts (see in > > tcp_v6_init_req()) > > > > The skb_clone_and_charge_r() happen later in tcp_v6_syn_recv_sock() > > > > The correct fix is to _not_ call skb_clone_and_charge_r() for a > > listener socket, of course, this never made _any_ sense. > > > > The following patch should fix both TCP and DCCP, and as a bonus make > > TCP SYN processing faster > > for listeners requesting these IPV6_PKTOPTIONS things. > Thank you very much for your suggestion and patch! > > However, the problem remains unsolved when I use the following patch to > test. > > Because skb_clone_and_charge_r() is still called when sk_state is > TCP_LISTEN in discard tag. > > So I modify the patch like this (it works after local test): SGTM, please send a V2 then.
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