netdev - Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net

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Message-ID: <69035c0b.050a0220.3344a1.0441.GAE@google.com>
Date: Thu, 30 Oct 2025 05:37:31 -0700
From: syzbot <syzbot+78ac1e46d2966eb70fda@...kaller.appspotmail.com>
To: coreteam@...filter.org, davem@...emloft.net, edumazet@...gle.com, 
	fw@...len.de, horms@...nel.org, kadlec@...filter.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	netfilter-devel@...r.kernel.org, pabeni@...hat.com, pablo@...filter.org, 
	phil@....cc, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net_hook (9)

syzbot has found a reproducer for the following issue on:

HEAD commit:    efd3e30e651d Merge branch 'net-stmmac-hwif-c-cleanups'
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17ea1704580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5683686a5f7ee53f
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
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12afbc92580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a6eb09423004/disk-efd3e30e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f8a2fb326497/vmlinux-efd3e30e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8cdcb8113e1/bzImage-efd3e30e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+78ac1e46d2966eb70fda@...kaller.appspotmail.com

------------[ cut here ]------------
hook not found, pf 5 num 0
WARNING: CPU: 1 PID: 9032 at net/netfilter/core.c:514 __nf_unregister_net_hook+0x30a/0x700 net/netfilter/core.c:514
Modules linked in:
CPU: 1 UID: 0 PID: 9032 Comm: syz.0.994 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:__nf_unregister_net_hook+0x30a/0x700 net/netfilter/core.c:514
Code: d5 18 f8 05 01 90 48 8b 44 24 10 0f b6 04 28 84 c0 0f 85 e3 03 00 00 41 8b 17 48 c7 c7 00 72 72 8c 44 89 ee e8 67 4f 14 f8 90 <0f> 0b 90 90 e9 d8 01 00 00 e8 a8 17 d7 01 89 c3 31 ff 89 c6 e8 fd
RSP: 0018:ffffc9000c396938 EFLAGS: 00010246
RAX: a02a0e56549ab800 RBX: ffff8880583d1480 RCX: ffff888059800000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: dffffc0000000000 R08: ffff8880b8924293 R09: 1ffff11017124852
R10: dffffc0000000000 R11: ffffed1017124853 R12: ffff88807acf2480
R13: 0000000000000005 R14: ffff88802701a488 R15: ffff88807796ae3c
FS:  00007fba157656c0(0000) GS:ffff888126240000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555576f79808 CR3: 000000007f6c4000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 nft_unregister_flowtable_ops net/netfilter/nf_tables_api.c:8979 [inline]
 nft_flowtable_event net/netfilter/nf_tables_api.c:9758 [inline]
 __nf_tables_flowtable_event+0x5bf/0x8c0 net/netfilter/nf_tables_api.c:9803
 nf_tables_flowtable_event+0x103/0x160 net/netfilter/nf_tables_api.c:9834
 notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 unregister_netdevice_many_notify+0x1860/0x2390 net/core/dev.c:12333
 unregister_netdevice_many net/core/dev.c:12396 [inline]
 unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12210
 unregister_netdevice include/linux/netdevice.h:3390 [inline]
 hsr_dev_finalize+0x707/0xaa0 net/hsr/hsr_device.c:800
 hsr_newlink+0x8ad/0x9f0 net/hsr/hsr_netlink.c:128
 rtnl_newlink_create+0x310/0xb00 net/core/rtnetlink.c:3833
 __rtnl_newlink net/core/rtnetlink.c:3950 [inline]
 rtnl_newlink+0x16e4/0x1c80 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6951
 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+0x505/0x830 net/socket.c:2630
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2684
 __sys_sendmsg net/socket.c:2716 [inline]
 __do_sys_sendmsg net/socket.c:2721 [inline]
 __se_sys_sendmsg net/socket.c:2719 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2719
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fba1498efc9
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:00007fba15765038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fba14be5fa0 RCX: 00007fba1498efc9
RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007fba14a11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fba14be6038 R14: 00007fba14be5fa0 R15: 00007ffcbfaff8c8
 </TASK>


---
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#syz test: git://repo/address.git branch-or-commit-hash
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