1. Patchew
  2. QEMU
  3. View series

[PATCH] net: Fix uninitialized data usage

Patrick Venture posted 1 patch 4 years, 1 month ago
Test checkpatch passed
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20220106182851.3583896-1-venture@google.com
Maintainers: Jason Wang <jasowang@redhat.com>
net/tap-linux.c | 1 +
1 file changed, 1 insertion(+)
[PATCH] net: Fix uninitialized data usage
Posted by Patrick Venture 4 years, 1 month ago 
From: Peter Foley <pefoley@google.com>

e.g.
1109 15:16:20.151506 Uninitialized bytes in ioctl_common_pre at offset 0 inside [0x7ffc516af9b8, 4)
 1109 15:16:20.151659 ==588974==WARNING: MemorySanitizer: use-of-uninitialized-value
 1109 15:16:20.312923     #0 0x5639b88acb21 in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c:183:9
 1109 15:16:20.312952     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
 1109 15:16:20.312954     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
 1109 15:16:20.312956     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
 1109 15:16:20.312957     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
 1109 15:16:20.312958     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
 1109 15:16:20.312960     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
 1109 15:16:20.312961     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
 1109 15:16:20.312962     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
 1109 15:16:20.312964     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
 1109 15:16:20.312965     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
 1109 15:16:20.312967     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
 1109 15:16:20.312968     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
 1109 15:16:20.312969     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
 1109 15:16:20.312970
 1109 15:16:20.312975   Uninitialized value was stored to memory at
 1109 15:16:20.313393     #0 0x5639b88acbee in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c
 1109 15:16:20.313396     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
 1109 15:16:20.313398     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
 1109 15:16:20.313399     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
 1109 15:16:20.313400     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
 1109 15:16:20.313401     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
 1109 15:16:20.313403     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
 1109 15:16:20.313404     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
 1109 15:16:20.313405     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
 1109 15:16:20.313407     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
 1109 15:16:20.313408     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
 1109 15:16:20.313409     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
 1109 15:16:20.313410     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
 1109 15:16:20.313412     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
 1109 15:16:20.313413
 1109 15:16:20.313417   Uninitialized value was stored to memory at
 1109 15:16:20.313791     #0 0x5639b88affbd in net_tap_fd_init third_party/qemu/net/tap.c:400:26
 1109 15:16:20.313826     #1 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
 1109 15:16:20.313829     #2 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
 1109 15:16:20.313831     #3 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
 1109 15:16:20.313836     #4 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
 1109 15:16:20.313838     #5 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
 1109 15:16:20.313839     #6 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
 1109 15:16:20.313841     #7 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
 1109 15:16:20.313843     #8 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
 1109 15:16:20.313844     #9 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
 1109 15:16:20.313845     #10 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
 1109 15:16:20.313846     #11 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
 1109 15:16:20.313847     #12 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
 1109 15:16:20.313849
 1109 15:16:20.313851   Uninitialized value was created by an allocation of 'ifr' in the stack frame of function 'tap_probe_vnet_hdr'
 1109 15:16:20.313855     #0 0x5639b88ac680 in tap_probe_vnet_hdr third_party/qemu/net/tap-linux.c:151
 1109 15:16:20.313856
 1109 15:16:20.313878 SUMMARY: MemorySanitizer: use-of-uninitialized-value third_party/qemu/net/tap-linux.c:183:9 in tap_probe_vnet_hdr_len

Fixes: dc69004c7d8 ("net: move tap_probe_vnet_hdr() to tap-linux.c")
Reviewed-by: Hao Wu <wuhaotsh@google.com>
Reviewed-by: Patrick Venture <venture@google.com>
Signed-off-by: Peter Foley <pefoley@google.com>
---
 net/tap-linux.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tap-linux.c b/net/tap-linux.c
index 9584769740..5e70b93037 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -150,6 +150,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 int tap_probe_vnet_hdr(int fd, Error **errp)
 {
     struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
 
     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
         /* TUNGETIFF is available since kernel v2.6.27 */
-- 
2.34.1.448.ga2b2bfdf31-goog
Re: [PATCH] net: Fix uninitialized data usage
Posted by Philippe Mathieu-Daudé 4 years, 1 month ago 
On 6/1/22 19:28, Patrick Venture wrote:
> From: Peter Foley <pefoley@google.com>
> 
> e.g.
> 1109 15:16:20.151506 Uninitialized bytes in ioctl_common_pre at offset 0 inside [0x7ffc516af9b8, 4)
>   1109 15:16:20.151659 ==588974==WARNING: MemorySanitizer: use-of-uninitialized-value
>   1109 15:16:20.312923     #0 0x5639b88acb21 in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c:183:9
>   1109 15:16:20.312952     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
>   1109 15:16:20.312954     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
>   1109 15:16:20.312956     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
>   1109 15:16:20.312957     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
>   1109 15:16:20.312958     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
>   1109 15:16:20.312960     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
>   1109 15:16:20.312961     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
>   1109 15:16:20.312962     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
>   1109 15:16:20.312964     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
>   1109 15:16:20.312965     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
>   1109 15:16:20.312967     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
>   1109 15:16:20.312968     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
>   1109 15:16:20.312969     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
>   1109 15:16:20.312970
>   1109 15:16:20.312975   Uninitialized value was stored to memory at
>   1109 15:16:20.313393     #0 0x5639b88acbee in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c
>   1109 15:16:20.313396     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
>   1109 15:16:20.313398     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
>   1109 15:16:20.313399     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
>   1109 15:16:20.313400     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
>   1109 15:16:20.313401     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
>   1109 15:16:20.313403     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
>   1109 15:16:20.313404     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
>   1109 15:16:20.313405     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
>   1109 15:16:20.313407     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
>   1109 15:16:20.313408     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
>   1109 15:16:20.313409     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
>   1109 15:16:20.313410     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
>   1109 15:16:20.313412     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
>   1109 15:16:20.313413
>   1109 15:16:20.313417   Uninitialized value was stored to memory at
>   1109 15:16:20.313791     #0 0x5639b88affbd in net_tap_fd_init third_party/qemu/net/tap.c:400:26
>   1109 15:16:20.313826     #1 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
>   1109 15:16:20.313829     #2 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
>   1109 15:16:20.313831     #3 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
>   1109 15:16:20.313836     #4 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
>   1109 15:16:20.313838     #5 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
>   1109 15:16:20.313839     #6 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
>   1109 15:16:20.313841     #7 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
>   1109 15:16:20.313843     #8 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
>   1109 15:16:20.313844     #9 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
>   1109 15:16:20.313845     #10 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
>   1109 15:16:20.313846     #11 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
>   1109 15:16:20.313847     #12 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
>   1109 15:16:20.313849
>   1109 15:16:20.313851   Uninitialized value was created by an allocation of 'ifr' in the stack frame of function 'tap_probe_vnet_hdr'
>   1109 15:16:20.313855     #0 0x5639b88ac680 in tap_probe_vnet_hdr third_party/qemu/net/tap-linux.c:151
>   1109 15:16:20.313856
>   1109 15:16:20.313878 SUMMARY: MemorySanitizer: use-of-uninitialized-value third_party/qemu/net/tap-linux.c:183:9 in tap_probe_vnet_hdr_len
> 
> Fixes: dc69004c7d8 ("net: move tap_probe_vnet_hdr() to tap-linux.c")
> Reviewed-by: Hao Wu <wuhaotsh@google.com>
> Reviewed-by: Patrick Venture <venture@google.com>
> Signed-off-by: Peter Foley <pefoley@google.com>
> ---
>   net/tap-linux.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/net/tap-linux.c b/net/tap-linux.c
> index 9584769740..5e70b93037 100644
> --- a/net/tap-linux.c
> +++ b/net/tap-linux.c
> @@ -150,6 +150,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
>   int tap_probe_vnet_hdr(int fd, Error **errp)
>   {
>       struct ifreq ifr;
> +    memset(&ifr, 0, sizeof(ifr));

Or:

        struct ifreq ifr = { };

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

>   
>       if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
>           /* TUNGETIFF is available since kernel v2.6.27 */
Re: [PATCH] net: Fix uninitialized data usage
Posted by Peter Foley 4 years, 1 month ago 
Yeah, but this same pattern is used elsewhere in the file, so I went with
being consistent.

On Thu, Jan 6, 2022, 2:44 PM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:

> On 6/1/22 19:28, Patrick Venture wrote:
> > From: Peter Foley <pefoley@google.com>
> >
> > e.g.
> > 1109 15:16:20.151506 Uninitialized bytes in ioctl_common_pre at offset 0
> inside [0x7ffc516af9b8, 4)
> >   1109 15:16:20.151659 ==588974==WARNING: MemorySanitizer:
> use-of-uninitialized-value
> >   1109 15:16:20.312923     #0 0x5639b88acb21 in tap_probe_vnet_hdr_len
> third_party/qemu/net/tap-linux.c:183:9
> >   1109 15:16:20.312952     #1 0x5639b88afd66 in net_tap_fd_init
> third_party/qemu/net/tap.c:409:9
> >   1109 15:16:20.312954     #2 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.312956     #3 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.312957     #4 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.312958     #5 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.312960     #6 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.312961     #7 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.312962     #8 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.312964     #9 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.312965     #10 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.312967     #11 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.312968     #12 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.312969     #13 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.312970
> >   1109 15:16:20.312975   Uninitialized value was stored to memory at
> >   1109 15:16:20.313393     #0 0x5639b88acbee in tap_probe_vnet_hdr_len
> third_party/qemu/net/tap-linux.c
> >   1109 15:16:20.313396     #1 0x5639b88afd66 in net_tap_fd_init
> third_party/qemu/net/tap.c:409:9
> >   1109 15:16:20.313398     #2 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.313399     #3 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.313400     #4 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.313401     #5 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.313403     #6 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.313404     #7 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.313405     #8 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.313407     #9 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.313408     #10 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.313409     #11 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.313410     #12 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.313412     #13 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.313413
> >   1109 15:16:20.313417   Uninitialized value was stored to memory at
> >   1109 15:16:20.313791     #0 0x5639b88affbd in net_tap_fd_init
> third_party/qemu/net/tap.c:400:26
> >   1109 15:16:20.313826     #1 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.313829     #2 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.313831     #3 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.313836     #4 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.313838     #5 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.313839     #6 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.313841     #7 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.313843     #8 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.313844     #9 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.313845     #10 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.313846     #11 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.313847     #12 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.313849
> >   1109 15:16:20.313851   Uninitialized value was created by an
> allocation of 'ifr' in the stack frame of function 'tap_probe_vnet_hdr'
> >   1109 15:16:20.313855     #0 0x5639b88ac680 in tap_probe_vnet_hdr
> third_party/qemu/net/tap-linux.c:151
> >   1109 15:16:20.313856
> >   1109 15:16:20.313878 SUMMARY: MemorySanitizer:
> use-of-uninitialized-value third_party/qemu/net/tap-linux.c:183:9 in
> tap_probe_vnet_hdr_len
> >
> > Fixes: dc69004c7d8 ("net: move tap_probe_vnet_hdr() to tap-linux.c")
> > Reviewed-by: Hao Wu <wuhaotsh@google.com>
> > Reviewed-by: Patrick Venture <venture@google.com>
> > Signed-off-by: Peter Foley <pefoley@google.com>
> > ---
> >   net/tap-linux.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/net/tap-linux.c b/net/tap-linux.c
> > index 9584769740..5e70b93037 100644
> > --- a/net/tap-linux.c
> > +++ b/net/tap-linux.c
> > @@ -150,6 +150,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions
> *tap, Error **errp)
> >   int tap_probe_vnet_hdr(int fd, Error **errp)
> >   {
> >       struct ifreq ifr;
> > +    memset(&ifr, 0, sizeof(ifr));
>
> Or:
>
>         struct ifreq ifr = { };
>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>
> >
> >       if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
> >           /* TUNGETIFF is available since kernel v2.6.27 */
>
>
Re: [PATCH] net: Fix uninitialized data usage
Posted by Jason Wang 4 years, 1 month ago 
On Fri, Jan 7, 2022 at 3:44 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 6/1/22 19:28, Patrick Venture wrote:
> > From: Peter Foley <pefoley@google.com>
> >
> > e.g.
> > 1109 15:16:20.151506 Uninitialized bytes in ioctl_common_pre at offset 0 inside [0x7ffc516af9b8, 4)
> >   1109 15:16:20.151659 ==588974==WARNING: MemorySanitizer: use-of-uninitialized-value
> >   1109 15:16:20.312923     #0 0x5639b88acb21 in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c:183:9
> >   1109 15:16:20.312952     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
> >   1109 15:16:20.312954     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.312956     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.312957     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.312958     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.312960     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.312961     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.312962     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.312964     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.312965     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.312967     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.312968     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.312969     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.312970
> >   1109 15:16:20.312975   Uninitialized value was stored to memory at
> >   1109 15:16:20.313393     #0 0x5639b88acbee in tap_probe_vnet_hdr_len third_party/qemu/net/tap-linux.c
> >   1109 15:16:20.313396     #1 0x5639b88afd66 in net_tap_fd_init third_party/qemu/net/tap.c:409:9
> >   1109 15:16:20.313398     #2 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.313399     #3 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.313400     #4 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.313401     #5 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.313403     #6 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.313404     #7 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.313405     #8 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.313407     #9 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.313408     #10 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.313409     #11 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.313410     #12 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.313412     #13 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.313413
> >   1109 15:16:20.313417   Uninitialized value was stored to memory at
> >   1109 15:16:20.313791     #0 0x5639b88affbd in net_tap_fd_init third_party/qemu/net/tap.c:400:26
> >   1109 15:16:20.313826     #1 0x5639b88b2d1b in net_init_tap_one third_party/qemu/net/tap.c:681:19
> >   1109 15:16:20.313829     #2 0x5639b88b16a8 in net_init_tap third_party/qemu/net/tap.c:912:13
> >   1109 15:16:20.313831     #3 0x5639b8890175 in net_client_init1 third_party/qemu/net/net.c:1110:9
> >   1109 15:16:20.313836     #4 0x5639b888f912 in net_client_init third_party/qemu/net/net.c:1208:15
> >   1109 15:16:20.313838     #5 0x5639b8894aa5 in net_param_nic third_party/qemu/net/net.c:1588:11
> >   1109 15:16:20.313839     #6 0x5639b900cd18 in qemu_opts_foreach third_party/qemu/util/qemu-option.c:1135:14
> >   1109 15:16:20.313841     #7 0x5639b889393c in net_init_clients third_party/qemu/net/net.c:1612:9
> >   1109 15:16:20.313843     #8 0x5639b717aaf3 in qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> >   1109 15:16:20.313844     #9 0x5639b717aaf3 in qemu_init third_party/qemu/softmmu/vl.c:3694:5
> >   1109 15:16:20.313845     #10 0x5639b71083b8 in main third_party/qemu/softmmu/main.c:49:5
> >   1109 15:16:20.313846     #11 0x7f464de1d8d2 in __libc_start_main (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> >   1109 15:16:20.313847     #12 0x5639b6bbd389 in _start /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> >   1109 15:16:20.313849
> >   1109 15:16:20.313851   Uninitialized value was created by an allocation of 'ifr' in the stack frame of function 'tap_probe_vnet_hdr'
> >   1109 15:16:20.313855     #0 0x5639b88ac680 in tap_probe_vnet_hdr third_party/qemu/net/tap-linux.c:151
> >   1109 15:16:20.313856
> >   1109 15:16:20.313878 SUMMARY: MemorySanitizer: use-of-uninitialized-value third_party/qemu/net/tap-linux.c:183:9 in tap_probe_vnet_hdr_len
> >
> > Fixes: dc69004c7d8 ("net: move tap_probe_vnet_hdr() to tap-linux.c")
> > Reviewed-by: Hao Wu <wuhaotsh@google.com>
> > Reviewed-by: Patrick Venture <venture@google.com>
> > Signed-off-by: Peter Foley <pefoley@google.com>
> > ---
> >   net/tap-linux.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/net/tap-linux.c b/net/tap-linux.c
> > index 9584769740..5e70b93037 100644
> > --- a/net/tap-linux.c
> > +++ b/net/tap-linux.c
> > @@ -150,6 +150,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
> >   int tap_probe_vnet_hdr(int fd, Error **errp)
> >   {
> >       struct ifreq ifr;
> > +    memset(&ifr, 0, sizeof(ifr));
>
> Or:
>
>         struct ifreq ifr = { };
>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Applied.

Thanks

>
> >
> >       if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
> >           /* TUNGETIFF is available since kernel v2.6.27 */
>

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.