WARNING in __dev_queue_xmit

Status: premoderation: reported C repro on 2026/08/08 00:18
Reported-by: syzbot+c99b6ca14fe3ad640857@syzkaller.appspotmail.com
First crash: 1d20h, last: 18h01m
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in __dev_queue_xmit (3) net -1 syz, C error inconclusive 20 1128d 1151d 0/29 auto-obsoleted due to no activity on 2023/11/09 02:33
linux-5.15 WARNING in __dev_queue_xmit -1 syz, C 107 662d 747d 0/3 auto-obsoleted due to no activity on 2024/12/25 04:54
upstream WARNING in __dev_queue_xmit (4) net -1 syz, C 387 657d 704d 28/29 fixed on 2024/10/22 11:57
upstream WARNING in __dev_queue_xmit -1 syz, C done 16774 1262d 1476d 22/29 fixed on 2023/02/24 14:17
upstream WARNING in __dev_queue_xmit (2) net -1 syz, C 76 1190d 1262d 22/29 fixed on 2023/06/08 14:41
upstream WARNING in __dev_queue_xmit (5) net -1 syz, C 41 601d 600d 28/29 fixed on 2025/05/06 15:33
linux-6.1 WARNING in __dev_queue_xmit (2) -1 syz, C 5 1d10h 1d19h 0/3 upstream: reported C repro on 2026/08/08 00:39
linux-6.1 WARNING in __dev_queue_xmit -1 43 662d 762d 0/3 auto-obsoleted due to no activity on 2024/12/25 04:13

Sample crash report:
------------[ cut here ]------------
skb_assert_len
WARNING: CPU: 0 PID: 314 at include/linux/skbuff.h:2720 skb_assert_len include/linux/skbuff.h:2720 [inline]
WARNING: CPU: 0 PID: 314 at include/linux/skbuff.h:2720 __dev_queue_xmit+0x1e1d/0x3780 net/core/dev.c:4462
Modules linked in:
CPU: 0 UID: 0 PID: 314 Comm: syz-executor306 Not tainted syzkaller #0 4d4a838cf2fc485b043991145ccf8426a0241c16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:skb_assert_len include/linux/skbuff.h:2720 [inline]
RIP: 0010:__dev_queue_xmit+0x1e1d/0x3780 net/core/dev.c:4462
Code: 00 00 00 fc ff df e9 ea e6 ff ff e8 bd ba 05 fd c6 05 e5 95 63 03 01 48 c7 c7 60 16 8b 86 48 c7 c6 15 62 19 87 e8 d3 92 82 fc <0f> 0b 80 3d ca 95 63 03 01 0f 84 af e3 ff ff e8 8f ba 05 fd c6 05
RSP: 0018:ffffc900011df6a0 EFLAGS: 00010246
RAX: d64f2a062041bd00 RBX: ffff888133710bb0 RCX: ffff8881067edf00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc900011df980 R08: ffffc900011df387 R09: 1ffff9200023be70
R10: dffffc0000000000 R11: fffff5200023be71 R12: 1ffff110266e216a
R13: ffff888133710b40 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555580e1e3c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000080 CR3: 0000000131dc6000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 dev_queue_xmit include/linux/netdevice.h:3141 [inline]
 packet_xmit+0x76/0x360 net/packet/af_packet.c:276
 tpacket_snd net/packet/af_packet.c:2938 [inline]
 packet_sendmsg+0x228b/0x56b0 net/packet/af_packet.c:3165
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x68a/0x700 net/socket.c:2216
 __do_sys_sendto net/socket.c:2228 [inline]
 __se_sys_sendto net/socket.c:2224 [inline]
 __x64_sys_sendto+0xe9/0x100 net/socket.c:2224
 x64_sys_call+0x2c2c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f12e9fc11c9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff23748188 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000200000000200 RCX: 00007f12e9fc11c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f12ea02c489 R08: 0000200000000000 R09: 0000000000000014
R10: 0000000004000010 R11: 0000000000000246 R12: 00007f12ea02c3f1
R13: 0000000000000001 R14: 00007fff237481e0 R15: 0000000000000003
 </TASK>
---[ end trace 0000000000000000 ]---
skb len=0 headroom=144 headlen=0 tailroom=240
mac=(144,0) mac_len=0 net=(144,-1) trans=-1
shinfo(txflags=0 nr_frags=0 gso(size=0 type=0 segs=0))
csum(0x0 start=0 offset=0 ip_summed=0 complete_sw=0 valid=0 level=0)
hash(0x0 sw=0 l4=0) proto=0x0010 pkttype=0 iif=0
priority=0x0 mark=0x0 alloc_cpu=0 vlan_all=0x0

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 01:09 android16-6.12 b54741372957 e4ef95d6 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/08 00:46 android16-6.12 b54741372957 e4ef95d6 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/09 02:26 android16-6.12 309759bcbe6d 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/08 06:16 android16-6.12 b54741372957 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/08 06:15 android16-6.12 b54741372957 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/08 00:17 android16-6.12 b54741372957 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
2026/08/08 00:17 android16-6.12 b54741372957 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in __dev_queue_xmit
* Struck through repros no longer work on HEAD.