[syzbot] [netfilter?] WARNING in nf_flow_table_extend_ct_timeout
From: syzbot <hidden>
Date: 2026-09-15 22:34:33
Also in:
lkml, netfilter-devel
Hello, syzbot found the following issue on: HEAD commit: 50d05c7c76c9 Merge tag 'landlock-7.3-rc3' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14ac428e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=521f7e7e2b974abde99a compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/daf497619736/disk-50d05c7c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/748fbd82f647/vmlinux-50d05c7c.xz kernel image: https://storage.googleapis.com/syzbot-assets/e61c59099d07/bzImage-50d05c7c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+521f7e7e2b974abde99a@syzkaller.appspotmail.com ------------[ cut here ]------------ 1 WARNING: net/netfilter/nf_flow_table_core.c:546 at nf_flow_table_extend_ct_timeout+0x1ee/0x2f0 net/netfilter/nf_flow_table_core.c:546, CPU#0: kworker/0:2/3335 Modules linked in: CPU: 0 UID: 0 PID: 3335 Comm: kworker/0:2 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/08/2026 Workqueue: events_power_efficient nf_flow_offload_work_gc RIP: 0010:nf_flow_table_extend_ct_timeout+0x1ee/0x2f0 net/netfilter/nf_flow_table_core.c:546 Code: 00 00 00 41 83 ff 06 0f 84 9a 00 00 00 41 83 ff 05 0f 85 b0 00 00 00 e8 70 d1 ab f7 41 bf 30 75 00 00 eb 0f e8 63 d1 ab f7 90 <0f> 0b 90 41 bf 01 00 00 00 48 c7 c0 80 f2 a0 8e 48 c1 e8 03 42 80 RSP: 0000:ffffc900040ff938 EFLAGS: 00010293 RAX: ffffffff8a1bf92d RBX: ffff88807da5be00 RCX: ffff88803247ddc0 RDX: 0000000000000000 RSI: ffffffff902f6960 RDI: 000000000000002f RBP: 0000000000039e60 R08: ffff88803247ddc0 R09: 0000000000000002 R10: 0000000000000011 R11: 0000000000000000 R12: dffffc0000000000 R13: 1ffff1100fb4b7d8 R14: ffff88807da5be48 R15: 000000000000002f FS: 0000000000000000(0000) GS:ffff888124cd2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000f7238c10 CR3: 000000007a894000 CR4: 00000000003526f0 DR0: ffffffffffffffff DR1: 00000000000001f7 DR2: 00000000ffffffff DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <TASK> nf_flow_offload_gc_step+0x545/0x7b0 net/netfilter/nf_flow_table_core.c:581 nf_flow_table_iterate+0x13c/0x1f0 net/netfilter/nf_flow_table_core.c:452 nf_flow_table_gc_run net/netfilter/nf_flow_table_core.c:604 [inline] nf_flow_offload_work_gc+0x22/0x70 net/netfilter/nf_flow_table_core.c:612 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> --- 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