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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9312ee76490d octeontx2-af: use unsigned int as iterator fo..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=114b88a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4b71a7f00d74e4f3
dashboard link: https://syzkaller.appspot.com/bug?extid=78ac1e46d2966eb70fda
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b381ecf9ad30/disk-9312ee76.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebd0e7846e92/vmlinux-9312ee76.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b9c68d721e9c/bzImage-9312ee76.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+78ac1e...@syzkaller.appspotmail.com

x_tables: ip6_tables: mh match: only valid for protocol 135
------------[ cut here ]------------
hook not found, pf 10 num 1
WARNING: CPU: 0 PID: 7813 at net/netfilter/core.c:514 __nf_unregister_net_hook+0x30a/0x700 net/netfilter/core.c:514
Modules linked in:
CPU: 0 UID: 0 PID: 7813 Comm: syz.1.502 Not tainted 6.16.0-rc7-syzkaller-01904-g9312ee76490d #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__nf_unregister_net_hook+0x30a/0x700 net/netfilter/core.c:514
Code: 58 59 ef 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 60 8f 98 8c 44 89 ee e8 07 46 e7 f7 90 <0f> 0b 90 90 e9 d8 01 00 00 e8 98 bf d3 01 89 c3 31 ff 89 c6 e8 1d
RSP: 0018:ffffc9000e8a7768 EFLAGS: 00010246
RAX: d399e8c7c2db4300 RBX: ffff8880688c2400 RCX: ffff88802c435a00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa6c R12: ffff888029a72440
R13: 000000000000000a R14: ffff888029a736c0 R15: ffffffff8c9a21fc
FS: 00007f5152aa66c0(0000) GS:ffff888125c12000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c34c54a CR3: 0000000027c74000 CR4: 00000000003526f0
Call Trace:
<TASK>
nf_unregister_net_hook net/netfilter/core.c:-1 [inline]
nf_unregister_net_hooks+0xcb/0x140 net/netfilter/core.c:610
synproxy_tg6_destroy+0x58/0xb0 net/ipv6/netfilter/ip6t_SYNPROXY.c:94
cleanup_entry+0x265/0x320 net/ipv6/netfilter/ip6_tables.c:669
translate_table+0x1e5f/0x2040 net/ipv6/netfilter/ip6_tables.c:744
do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
do_ip6t_set_ctl+0x970/0xce0 net/ipv6/netfilter/ip6_tables.c:1644
nf_setsockopt+0x26f/0x290 net/netfilter/nf_sockopt.c:101
do_sock_setsockopt+0x179/0x1b0 net/socket.c:2344
__sys_setsockopt net/socket.c:2369 [inline]
__do_sys_setsockopt net/socket.c:2375 [inline]
__se_sys_setsockopt net/socket.c:2372 [inline]
__x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2372
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5151b8e9a9
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:00007f5152aa6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f5151db6080 RCX: 00007f5151b8e9a9
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 000000000000000d
RBP: 00007f5151c10d69 R08: 0000000000000470 R09: 0000000000000000
R10: 0000200000000480 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5151db6080 R15: 00007ffc85b4e498
</TASK>


---
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[syzbot]

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+78ac1e...@syzkaller.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>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

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***

Subject: Re: [syzbot] [netfilter?] WARNING in __nf_unregister_net_hook (9)
Author: ph...@nwl.cc

#syz test

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+78ac1e...@syzkaller.appspotmail.com
Tested-by: syzbot+78ac1e...@syzkaller.appspotmail.com

Tested on:

commit: 12a7c6a9 Merge tag 'nf-next-25-10-30' of https://git.k..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12f74e14580000

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

patch: https://syzkaller.appspot.com/x/patch.diff?x=11b3cbcd980000

Note: testing is done by a robot and is best-effort only.

[syzbot]

[syzbot]

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: 0 PID: 36 at net/netfilter/core.c:329 nf_hook_entry_head+0x23e/0x2c0 net/netfilter/core.c:329
Modules linked in:
CPU: 0 UID: 0 PID: 36 Comm: kworker/u8:2 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 7d b9 b6 f8 4d 39 37 74 36 e8 53 04 51 f8 90 <0f> 0b 90 31 db 48 89 d8 5b 41 5e 41 5f 5d c3 cc cc cc cc cc e8 39
RSP: 0018:ffffc90000ac7768 EFLAGS: 00010293
RAX: ffffffff896eff5b RBX: ffff888030a98000 RCX: ffff8881416b9e40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff8881416b9e40 R09: 0000000000000006
R10: 000000000000000a R11: 0000000000000000 R12: ffff888020ec8000
R13: 0000000000000005 R14: ffff888020ec8000 R15: ffff888030a98108
FS: 0000000000000000(0000) GS:ffff88812613e000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f2e4b7156c0 CR3: 000000000dd38000 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: 0d0eb186 cxgb4: flower: add support for fragmentation
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=162a7fe2580000

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

Note: no patches were applied.

[syzbot]

[syzbot]

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