WARNING in sit_tunnel_xmit

Status: premoderation: reported C repro on 2026/08/22 03:45
Reported-by: syzbot+c025893928108aec5216@syzkaller.appspotmail.com
First crash: 8d13h, last: 8d10h

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 314 at include/linux/skbuff.h:2824 pskb_may_pull_reason include/linux/skbuff.h:2824 [inline]
WARNING: CPU: 1 PID: 314 at include/linux/skbuff.h:2824 pskb_may_pull include/linux/skbuff.h:2840 [inline]
WARNING: CPU: 1 PID: 314 at include/linux/skbuff.h:2824 pskb_network_may_pull include/linux/skbuff.h:3199 [inline]
WARNING: CPU: 1 PID: 314 at include/linux/skbuff.h:2824 pskb_inet_may_pull include/net/ip_tunnels.h:466 [inline]
WARNING: CPU: 1 PID: 314 at include/linux/skbuff.h:2824 sit_tunnel_xmit+0x18b2/0x1f00 net/ipv6/sit.c:1071
Modules linked in:
CPU: 1 UID: 0 PID: 314 Comm: syz-executor407 Not tainted syzkaller #0 9a2c17613351c9eac8e18d74829f474689ac6bc1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:pskb_may_pull_reason include/linux/skbuff.h:2824 [inline]
RIP: 0010:pskb_may_pull include/linux/skbuff.h:2840 [inline]
RIP: 0010:pskb_network_may_pull include/linux/skbuff.h:3199 [inline]
RIP: 0010:pskb_inet_may_pull include/net/ip_tunnels.h:466 [inline]
RIP: 0010:sit_tunnel_xmit+0x18b2/0x1f00 net/ipv6/sit.c:1071
Code: 24 10 48 8b 7c 24 18 e8 1c fd 78 ff 48 8b 74 24 08 4c 8b 74 24 28 e9 fd f4 ff ff e8 28 d5 7a fc e9 b6 fa ff ff e8 1e d5 7a fc <0f> 0b e9 f7 e8 ff ff 44 89 ff 44 89 f6 e8 cc d6 7a fc 45 39 f7 0f
RSP: 0018:ffffc9000119f1a0 EFLAGS: 00010293
RAX: ffffffff850c9ca2 RBX: 0000000000000000 RCX: ffff8881334b3900
RDX: 0000000000000000 RSI: 00000000ffffff80 RDI: 0000000000000000
RBP: ffffc9000119f340 R08: ffff8881334b3900 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff850c83f0 R12: 1ffff11021e6da8e
R13: dffffc0000000000 R14: ffff88810f36d3c0 R15: 00000000ffffff80
FS:  0000555581f563c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000012281c000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 __netdev_start_xmit include/linux/netdevice.h:5008 [inline]
 netdev_start_xmit include/linux/netdevice.h:5017 [inline]
 __dev_direct_xmit+0x395/0x5a0 net/core/dev.c:4614
 __xsk_generic_xmit net/xdp/xsk.c:826 [inline]
 xsk_generic_xmit+0x1bef/0x3060 net/xdp/xsk.c:868
 xsk_poll+0x2ca/0x580 net/xdp/xsk.c:999
 sock_poll+0x23b/0x400 net/socket.c:1414
 vfs_poll include/linux/poll.h:92 [inline]
 do_select+0xe7f/0x16f0 fs/select.c:535
 core_sys_select+0x549/0x7f0 fs/select.c:678
 do_pselect fs/select.c:760 [inline]
 __do_sys_pselect6 fs/select.c:803 [inline]
 __se_sys_pselect6+0x268/0x320 fs/select.c:794
 __x64_sys_pselect6+0xe9/0x110 fs/select.c:794
 x64_sys_call+0x2980/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:271
 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: 0033:0x7fdac117c389
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:00007fffa98a2408 EFLAGS: 00000246 ORIG_RAX: 000000000000010e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdac117c389
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 0000000000000040
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000240 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
---[ end trace 0000000000000000 ]---

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/22 05:52 android16-6.12 e8c85685a629 1e72964b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in sit_tunnel_xmit
2026/08/22 05:08 android16-6.12 e8c85685a629 1e72964b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in sit_tunnel_xmit
2026/08/22 04:26 android16-6.12 e8c85685a629 1e72964b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in sit_tunnel_xmit
2026/08/22 03:44 android16-6.12 e8c85685a629 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in sit_tunnel_xmit
* Struck through repros no longer work on HEAD.