[syzbot] [netfilter?] WARNING in nf_conntrack_cleanup_net_list (2)
From: syzbot <hidden>
Date: 2026-05-29 20:02:22
Also in:
lkml, netfilter-devel
Hello, syzbot found the following issue on: HEAD commit: d60ec36cab33 Merge tag 'mm-hotfixes-stable-2026-05-25-16-2.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17f1712e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e327ee9a867dd6b9 dashboard link: https://syzkaller.appspot.com/bug?extid=122256c3e2bf6ec9f928 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d60ec36c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f8c1a87b3686/vmlinux-d60ec36c.xz kernel image: https://storage.googleapis.com/syzbot-assets/731575988634/bzImage-d60ec36c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+122256c3e2bf6ec9f928@syzkaller.appspotmail.com ------------[ cut here ]------------ conntrack cleanup blocked for 60s WARNING: net/netfilter/nf_conntrack_core.c:2506 at nf_conntrack_cleanup_net_list+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2506, CPU#2: kworker/u32:12/10858 Modules linked in: CPU: 2 UID: 0 PID: 10858 Comm: kworker/u32:12 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: netns cleanup_net RIP: 0010:nf_conntrack_cleanup_net_list+0x4f7/0x690 net/netfilter/nf_conntrack_core.c:2506 Code: 29 c3 48 89 de e8 a9 84 58 f8 48 85 db 78 0f e8 bf 89 58 f8 e8 ea 64 dc 01 e9 0e fc ff ff e8 b0 89 58 f8 48 8d 3d 39 7f 36 07 <67> 48 0f b9 3a eb de 4c 8b 6c 24 40 e8 98 89 58 f8 48 b8 00 00 00 RSP: 0018:ffffc90004057968 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffffffffffffff RCX: ffffffff89b02597 RDX: ffff888042c5ca00 RSI: ffffffff89b025b0 RDI: ffffffff90e6a4f0 RBP: 0000000000000001 R08: 0000000000000007 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000001 R14: ffffc90004057b20 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880d656a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c360d0b CR3: 000000004064f000 CR4: 0000000000352ef0 DR0: 0000000000000009 DR1: 00000000000000c9 DR2: 00000000000000f3 DR3: 00000000000000c0 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <TASK> ops_exit_list net/core/net_namespace.c:205 [inline] ops_undo_list+0x363/0xab0 net/core/net_namespace.c:252 cleanup_net+0x499/0x920 net/core/net_namespace.c:702 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314 process_scheduled_works kernel/workqueue.c:3397 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 29 c3 sub %eax,%ebx 2: 48 89 de mov %rbx,%rsi 5: e8 a9 84 58 f8 call 0xf85884b3 a: 48 85 db test %rbx,%rbx d: 78 0f js 0x1e f: e8 bf 89 58 f8 call 0xf85889d3 14: e8 ea 64 dc 01 call 0x1dc6503 19: e9 0e fc ff ff jmp 0xfffffc2c 1e: e8 b0 89 58 f8 call 0xf85889d3 23: 48 8d 3d 39 7f 36 07 lea 0x7367f39(%rip),%rdi # 0x7367f63 * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: eb de jmp 0xf 31: 4c 8b 6c 24 40 mov 0x40(%rsp),%r13 36: e8 98 89 58 f8 call 0xf85889d3 3b: 48 rex.W 3c: b8 .byte 0xb8 3d: 00 00 add %al,(%rax) --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup