Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net_hook (9)

[syzbot <syzbot+78ac1e46d2966eb70fda@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in nf_hook_entry_head

------------[ cut here ]------------
WARNING: CPU: 1 PID: 13 at net/netfilter/core.c:329 nf_hook_entry_head+0x23e/0x2c0 net/netfilter/core.c:329
Modules linked in:
CPU: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: netns cleanup_net
RIP: 0010:nf_hook_entry_head+0x23e/0x2c0 net/netfilter/core.c:329
Code: 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 ff e8 4d a5 b6 f8 4d 39 37 74 36 e8 23 f0 50 f8 90 <0f> 0b 90 31 db 48 89 d8 5b 41 5e 41 5f 5d e9 3f 00 da 01 cc e8 09
RSP: 0018:ffffc90000127768 EFLAGS: 00010293
RAX: ffffffff896f140b RBX: ffff888031eda000 RCX: ffff88801caa0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff88801caa0000 R09: 0000000000000006
R10: 000000000000000a R11: 0000000000000000 R12: ffff8880742e8000
R13: 0000000000000005 R14: ffff8880742e8000 R15: ffff888031eda108
FS:  0000000000000000(0000) GS:ffff88812623e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555728d3588 CR3: 0000000026f40000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __nf_unregister_net_hook+0x74/0x700 net/netfilter/core.c:491
 nft_unregister_flowtable_ops net/netfilter/nf_tables_api.c:8977 [inline]
 __nft_unregister_flowtable_net_hooks net/netfilter/nf_tables_api.c:8992 [inline]
 __nft_release_hook+0x180/0x350 net/netfilter/nf_tables_api.c:11985
 __nft_release_hooks net/netfilter/nf_tables_api.c:11999 [inline]
 nf_tables_pre_exit_net+0xa7/0x110 net/netfilter/nf_tables_api.c:12150
 ops_pre_exit_list net/core/net_namespace.c:161 [inline]
 ops_undo_list+0x187/0x990 net/core/net_namespace.c:234
 cleanup_net+0x4d8/0x820 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


Tested on:

commit:         1a2352ad Merge git://git.kernel.org/pub/scm/linux/kern..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1557d932580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=810aeb811fb1cca1
dashboard link: https://syzkaller.appspot.com/bug?extid=78ac1e46d2966eb70fda
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Note: no patches were applied.