WARNING in nf_conntrack_cleanup_net_list (2)

Status: upstream: reported on 2026/05/29 20:02
Subsystems: netfilter
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+122256c3e2bf6ec9f928@syzkaller.appspotmail.com
First crash: 148d, last: 11h10m
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
6f1f5e68 repro-c 💥 WARNING in nf_conntrack_cleanup_net_list (2) 2026/10/19 02:11 2026/10/19 02:11 2026/10/19 03:45 432c0077
8402b387 repro-c 💥 WARNING in nf_conntrack_cleanup_net_list (2) 2026/10/17 02:32 2026/10/17 02:32 2026/10/17 03:48 432c0077
5c37299a assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING in nf_conntrack_cleanup_net_list (2) 2026/05/29 23:15 2026/05/29 23:15 2026/05/29 23:51 6b4a8443
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[syzbot] Monthly netfilter report (Aug 2026) 0 (1) 2026/08/02 00:00
[syzbot] Monthly netfilter report (Jul 2026) 0 (1) 2026/07/01 12:32
[syzbot] [netfilter?] WARNING in nf_conntrack_cleanup_net_list (2) 0 (1) 2026/05/29 20:02
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in nf_conntrack_cleanup_net_list netfilter -1 765 180d 315d 29/29 fixed on 2026/05/06 16:40

Sample crash report:
------------[ cut here ]------------
conntrack cleanup blocked for 60s
WARNING: net/netfilter/nf_conntrack_core.c:2505 at nf_conntrack_cleanup_net_list+0x21f/0x360 net/netfilter/nf_conntrack_core.c:2504, CPU#0: kworker/u8:41/23108
Modules linked in:
CPU: 0 UID: 0 PID: 23108 Comm: kworker/u8:41 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: netns cleanup_net
RIP: 0010:nf_conntrack_cleanup_net_list+0x21f/0x360 net/netfilter/nf_conntrack_core.c:2504
Code: 4c 89 ef e8 63 6e 35 f8 4d 8b 7d 00 4d 39 ef 74 69 e8 95 8e c4 f7 45 31 e4 e9 a5 fe ff ff e8 88 8e c4 f7 48 8d 3d c1 b1 86 07 <67> 48 0f b9 3a eb c0 89 e9 80 e1 07 80 c1 03 38 c1 0f 8c da fe ff
RSP: 0018:ffffc900057178b0 EFLAGS: 00010293
RAX: ffffffff8a038298 RBX: dffffc0000000000 RCX: ffff88802ae00000
RDX: 0000000000000000 RSI: fffffffffffffffd RDI: ffffffff918a3460
RBP: 0000000000000001 R08: ffff888050f3b803 R09: 1ffff1100a1e7700
R10: dffffc0000000000 R11: ffffed100a1e7701 R12: 000000010001a8db
R13: ffffc90005717a50 R14: ffffc90005717a50 R15: 000000010001a8de
FS:  0000000000000000(0000) GS:ffff888123abf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f64efbfd7f4 CR3: 000000003438a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 08c5d32ffc85c5bc
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ops_exit_list net/core/net_namespace.c:206 [inline]
 ops_undo_list+0x4b4/0x8d0 net/core/net_namespace.c:253
 cleanup_net+0x572/0x810 net/core/net_namespace.c:706
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	4c 89 ef             	mov    %r13,%rdi
   3:	e8 63 6e 35 f8       	call   0xf8356e6b
   8:	4d 8b 7d 00          	mov    0x0(%r13),%r15
   c:	4d 39 ef             	cmp    %r13,%r15
   f:	74 69                	je     0x7a
  11:	e8 95 8e c4 f7       	call   0xf7c48eab
  16:	45 31 e4             	xor    %r12d,%r12d
  19:	e9 a5 fe ff ff       	jmp    0xfffffec3
  1e:	e8 88 8e c4 f7       	call   0xf7c48eab
  23:	48 8d 3d c1 b1 86 07 	lea    0x786b1c1(%rip),%rdi        # 0x786b1eb
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb c0                	jmp    0xfffffff1
  31:	89 e9                	mov    %ebp,%ecx
  33:	80 e1 07             	and    $0x7,%cl
  36:	80 c1 03             	add    $0x3,%cl
  39:	38 c1                	cmp    %al,%cl
  3b:	0f                   	.byte 0xf
  3c:	8c da                	mov    %ds,%edx
  3e:	fe                   	(bad)
  3f:	ff                   	.byte 0xff

Crashes (34):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/17 07:22 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/17 06:51 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/17 06:11 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/17 04:58 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/16 17:44 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/16 09:35 upstream 2f2f7eeef8b0 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/16 09:28 upstream 2f2f7eeef8b0 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in nf_conntrack_cleanup_net_list
2026/10/16 09:24 upstream 2f2f7eeef8b0 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in nf_conntrack_cleanup_net_list
2026/10/16 09:23 upstream 2f2f7eeef8b0 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in nf_conntrack_cleanup_net_list
2026/07/26 20:54 upstream 3dab139d4795 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in nf_conntrack_cleanup_net_list
2026/06/28 01:50 upstream 780d569e6c4b fb92f11c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in nf_conntrack_cleanup_net_list
2026/10/17 12:00 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/17 11:58 upstream 70dd4ee72eb2 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/16 22:36 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/16 17:44 upstream 2f2f7eeef8b0 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/16 06:08 upstream 045958acaa75 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/21 14:41 upstream a804c5742bff 42e06812 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in nf_conntrack_cleanup_net_list
2026/05/27 09:38 upstream d60ec36cab33 2b01f00e .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in nf_conntrack_cleanup_net_list
2026/10/20 06:55 upstream c03c1a14507d 21286ae2 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in nf_conntrack_cleanup_net_list
2026/10/22 11:37 net abeacca61eea 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 07:19 net abeacca61eea 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 07:17 net abeacca61eea 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/16 15:00 net 191aa41548b2 b1757810 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/08/13 19:14 net 9006c116dd11 a9ede23c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 10:10 net-next 279d5c8afcd3 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 04:33 net-next 279d5c8afcd3 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 02:26 net-next 279d5c8afcd3 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 02:22 net-next 279d5c8afcd3 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 02:18 net-next 279d5c8afcd3 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 02:18 net-next 279d5c8afcd3 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/19 03:22 net-next 98c2ad4f5d80 432c0077 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/16 07:27 net-next 6b3e73774815 3f2522c6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce WARNING in nf_conntrack_cleanup_net_list
2026/10/22 10:00 linux-next 9a482184d910 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in nf_conntrack_cleanup_net_list
2026/10/22 09:44 linux-next 9a482184d910 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING in nf_conntrack_cleanup_net_list
* Struck through repros no longer work on HEAD.