Re: [syzbot] [bridge?] KMSAN: uninit-value in netif_skb_features (4)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+1543a7...@syzkaller.appspotmail.com
Tested-by: syzbot+1543a7...@syzkaller.appspotmail.com

Tested on:

commit: 4ae12d8b Merge tag 'kbuild-fixes-7.0-2' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17616b5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=242f02fcd3fbc8f3
dashboard link: https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=1789d8d6580000

Note: testing is done by a robot and is best-effort only.

[Guoyu Su]

#syz test

[Scars]

#syz test

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+1543a7...@syzkaller.appspotmail.com
Tested-by: syzbot+1543a7...@syzkaller.appspotmail.com

Tested on:

commit: c23719ab Merge tag 'x86-urgent-2026-03-08' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17af0806580000

kernel config: https://syzkaller.appspot.com/x/.config?x=242f02fcd3fbc8f3
dashboard link: https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=101d3fe6580000

[Scars]

#syz test

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in netif_skb_features

=====================================================
BUG: KMSAN: uninit-value in gso_features_check net/core/dev.c:3816 [inline]
BUG: KMSAN: uninit-value in netif_skb_features+0x15fc/0x1a50 net/core/dev.c:3841
gso_features_check net/core/dev.c:3816 [inline]
netif_skb_features+0x15fc/0x1a50 net/core/dev.c:3841
validate_xmit_skb+0xb6/0x2400 net/core/dev.c:4016
validate_xmit_skb_list+0xd4/0x320 net/core/dev.c:4078
sch_direct_xmit+0xd4/0xcf0 net/sched/sch_generic.c:332
__dev_xmit_skb net/core/dev.c:4192 [inline]
__dev_queue_xmit+0x301d/0x5980 net/core/dev.c:4808
dev_queue_xmit include/linux/netdevice.h:3384 [inline]
packet_xmit+0x8f/0x710 net/packet/af_packet.c:275
packet_snd net/packet/af_packet.c:3076 [inline]
packet_sendmsg+0x91d9/0xa320 net/packet/af_packet.c:3108
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xf37/0xfd0 net/socket.c:2592
___sys_sendmsg+0x271/0x3b0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2681
x64_sys_call+0x1e20/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4549 [inline]
slab_alloc_node mm/slub.c:4869 [inline]
kmem_cache_alloc_node_noprof+0x3cd/0x12d0 mm/slub.c:4921
kmalloc_reserve net/core/skbuff.c:613 [inline]
__alloc_skb+0x855/0x1190 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6763
sock_alloc_send_pskb+0xacb/0xc60 net/core/sock.c:2995
packet_alloc_skb net/packet/af_packet.c:2926 [inline]
packet_snd net/packet/af_packet.c:3019 [inline]
packet_sendmsg+0x7477/0xa320 net/packet/af_packet.c:3108
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xf37/0xfd0 net/socket.c:2592
___sys_sendmsg+0x271/0x3b0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2681
x64_sys_call+0x1e20/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6599 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
=====================================================


Tested on:

commit: 80234b5a Merge tag 'rproc-v7.0-fixes' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109504d6580000

kernel config: https://syzkaller.appspot.com/x/.config?x=242f02fcd3fbc8f3
dashboard link: https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=1241b75a580000