linux-kernel - Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [day] [month] [year] [list]
Message-ID: <696a53da.050a0220.58bed.0053.GAE@google.com>
Date: Fri, 16 Jan 2026 07:06:02 -0800
From: syzbot <syzbot+78ac1e46d2966eb70fda@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, phil@....cc, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net_hook (9)

Hello,

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

------------[ cut here ]------------
hook not found, pf 5 num 0
WARNING: net/netfilter/core.c:516 at __nf_unregister_net_hook+0x2c5/0x6f0 net/netfilter/core.c:516, CPU#1: syz.2.927/9538
Modules linked in:
CPU: 1 UID: 0 PID: 9538 Comm: syz.2.927 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__nf_unregister_net_hook+0x2dc/0x6f0 net/netfilter/core.c:516
Code: 24 30 48 8b 5c 24 08 44 8b 6c 24 04 48 8d 3d 1b e4 10 06 48 8b 44 24 10 0f b6 04 28 84 c0 0f 85 f1 02 00 00 41 8b 17 44 89 ee <67> 48 0f b9 3a e9 db 01 00 00 e8 15 4e da 01 89 c3 31 ff 89 c6 e8
RSP: 0018:ffffc9000bb86938 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888024644d00 RCX: ffff88801e7e9e80
RDX: 0000000000000000 RSI: 0000000000000005 RDI: ffffffff8f90dc70
RBP: dffffc0000000000 R08: ffffffff8f823877 R09: 1ffffffff1f0470e
R10: dffffc0000000000 R11: fffffbfff1f0470f R12: ffff88801dbea5c0
R13: 0000000000000005 R14: ffff88807cc48488 R15: ffff888077a0e53c
FS:  00007f13330c66c0(0000) GS:ffff888125f1c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000200 CR3: 000000007b3ee000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 nft_unregister_flowtable_ops net/netfilter/nf_tables_api.c:9039 [inline]
 nft_flowtable_event net/netfilter/nf_tables_api.c:9818 [inline]
 __nf_tables_flowtable_event+0x5bf/0x8c0 net/netfilter/nf_tables_api.c:9863
 nf_tables_flowtable_event+0x103/0x160 net/netfilter/nf_tables_api.c:9894
 notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2280 [inline]
 call_netdevice_notifiers net/core/dev.c:2294 [inline]
 unregister_netdevice_many_notify+0x1867/0x2340 net/core/dev.c:12395
 unregister_netdevice_many net/core/dev.c:12458 [inline]
 unregister_netdevice_queue+0x317/0x350 net/core/dev.c:12272
 unregister_netdevice include/linux/netdevice.h:3405 [inline]
 hsr_dev_finalize+0x707/0xaa0 net/hsr/hsr_device.c:823
 hsr_newlink+0x8ad/0x9f0 net/hsr/hsr_netlink.c:128
 rtnl_newlink_create+0x310/0xb00 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x16e7/0x1c90 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 ____sys_sendmsg+0x505/0x820 net/socket.c:2592
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2681
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f133218efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f13330c6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f13323e5fa0 RCX: 00007f133218efc9
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007f1332211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f13323e6038 R14: 00007f13323e5fa0 R15: 00007ffc243e1258
 </TASK>
----------------
Code disassembly (best guess):
   0:	24 30                	and    $0x30,%al
   2:	48 8b 5c 24 08       	mov    0x8(%rsp),%rbx
   7:	44 8b 6c 24 04       	mov    0x4(%rsp),%r13d
   c:	48 8d 3d 1b e4 10 06 	lea    0x610e41b(%rip),%rdi        # 0x610e42e
  13:	48 8b 44 24 10       	mov    0x10(%rsp),%rax
  18:	0f b6 04 28          	movzbl (%rax,%rbp,1),%eax
  1c:	84 c0                	test   %al,%al
  1e:	0f 85 f1 02 00 00    	jne    0x315
  24:	41 8b 17             	mov    (%r15),%edx
  27:	44 89 ee             	mov    %r13d,%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 db 01 00 00       	jmp    0x20f
  34:	e8 15 4e da 01       	call   0x1da4e4e
  39:	89 c3                	mov    %eax,%ebx
  3b:	31 ff                	xor    %edi,%edi
  3d:	89 c6                	mov    %eax,%esi
  3f:	e8                   	.byte 0xe8


Tested on:

commit:         74ecff77 xgbe: Use netlink extack to report errors to ..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=163f0852580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=70d5cf3628e49ccb
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
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13e15a3a580000