[syzbot] WARNING in __nf_unregister_net_hook (4)

[syzbot] WARNING in __nf_unregister_net_hook (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    cc0626c2 net: smsc911x: skip acpi_device_id table when !CO..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=110a3096d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7eff0f22b8563a5f
dashboard link: https://syzkaller.appspot.com/bug?extid=154bd5be532a63aa778b

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com

hook not found, pf 2 num 0
WARNING: CPU: 1 PID: 8144 at net/netfilter/core.c:480 __nf_unregister_net_hook+0x1eb/0x610 net/netfilter/core.c:480
Modules linked in:
CPU: 1 PID: 8144 Comm: syz-executor.0 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__nf_unregister_net_hook+0x1eb/0x610 net/netfilter/core.c:480
Code: 0f b6 14 02 48 89 c8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 11 04 00 00 8b 53 1c 89 ee 48 c7 c7 e0 26 6c 8a e8 72 df 87 01 <0f> 0b e9 e5 00 00 00 e8 09 1d 37 fa 44 8b 3c 24 4c 89 f8 48 c1 e0
RSP: 0018:ffffc9001534f418 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88802f867a00 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815c5205 RDI: fffff52002a69e75
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815bdf9e R11: 0000000000000000 R12: ffff8880272c8f20
R13: 0000000000000000 R14: ffff88802fa34c00 R15: 0000000000000006
FS:  00007feaf7d10700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb651f70ca0 CR3: 0000000069f31000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 nf_unregister_net_hook+0xd5/0x110 net/netfilter/core.c:502
 nf_tables_unregister_hook.part.0+0x131/0x200 net/netfilter/nf_tables_api.c:234
 nf_tables_unregister_hook net/netfilter/nf_tables_api.c:8122 [inline]
 nf_tables_commit+0x1d9b/0x4710 net/netfilter/nf_tables_api.c:8122
 nfnetlink_rcv_batch+0x975/0x21b0 net/netfilter/nfnetlink.c:508
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:580 [inline]
 nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:598
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007feaf7d10188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 000000002000c2c0 RDI: 0000000000000003
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe0fcaf04f R14: 00007feaf7d10300 R15: 0000000000022000


---
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.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Dmitry Vyukov]

On Sat, Apr 10, 2021 at 4:49 PM syzbot
<syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    cc0626c2 net: smsc911x: skip acpi_device_id table when !CO..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=110a3096d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=7eff0f22b8563a5f
> dashboard link: https://syzkaller.appspot.com/bug?extid=154bd5be532a63aa778b
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com

Is this also fixed by "netfilter: arptables: use pernet ops struct
during unregister"?
The warning is the same, but the stack is different...

> hook not found, pf 2 num 0
> WARNING: CPU: 1 PID: 8144 at net/netfilter/core.c:480 __nf_unregister_net_hook+0x1eb/0x610 net/netfilter/core.c:480
> Modules linked in:
> CPU: 1 PID: 8144 Comm: syz-executor.0 Not tainted 5.12.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__nf_unregister_net_hook+0x1eb/0x610 net/netfilter/core.c:480
> Code: 0f b6 14 02 48 89 c8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 11 04 00 00 8b 53 1c 89 ee 48 c7 c7 e0 26 6c 8a e8 72 df 87 01 <0f> 0b e9 e5 00 00 00 e8 09 1d 37 fa 44 8b 3c 24 4c 89 f8 48 c1 e0
> RSP: 0018:ffffc9001534f418 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff88802f867a00 RCX: 0000000000000000
> RDX: 0000000000040000 RSI: ffffffff815c5205 RDI: fffff52002a69e75
> RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff815bdf9e R11: 0000000000000000 R12: ffff8880272c8f20
> R13: 0000000000000000 R14: ffff88802fa34c00 R15: 0000000000000006
> FS:  00007feaf7d10700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fb651f70ca0 CR3: 0000000069f31000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  nf_unregister_net_hook+0xd5/0x110 net/netfilter/core.c:502
>  nf_tables_unregister_hook.part.0+0x131/0x200 net/netfilter/nf_tables_api.c:234
>  nf_tables_unregister_hook net/netfilter/nf_tables_api.c:8122 [inline]
>  nf_tables_commit+0x1d9b/0x4710 net/netfilter/nf_tables_api.c:8122
>  nfnetlink_rcv_batch+0x975/0x21b0 net/netfilter/nfnetlink.c:508
>  nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:580 [inline]
>  nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:598
>  netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
>  netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
>  netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
>  sock_sendmsg_nosec net/socket.c:654 [inline]
>  sock_sendmsg+0xcf/0x120 net/socket.c:674
>  ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
>  ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
>  __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x466459
> 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007feaf7d10188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
> RDX: 0000000000000000 RSI: 000000002000c2c0 RDI: 0000000000000003
> RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
> R13: 00007ffe0fcaf04f R14: 00007feaf7d10300 R15: 0000000000022000
>
>
> ---
> 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.
>
> --
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Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Florian Westphal]

Dmitry Vyukov <dvyukov@google.com> wrote:
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> 
> Is this also fixed by "netfilter: arptables: use pernet ops struct
> during unregister"?
> The warning is the same, but the stack is different...

No, this is a different bug.

In both cases the caller attempts to unregister a hook that the core
can't find, but in this case the caller is nftables, not arptables.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Pablo Neira Ayuso]

On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> Dmitry Vyukov <dvyukov@google.com> wrote:
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > 
> > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > during unregister"?
> > The warning is the same, but the stack is different...
> 
> No, this is a different bug.
> 
> In both cases the caller attempts to unregister a hook that the core
> can't find, but in this case the caller is nftables, not arptables.

I see no reproducer for this bug. Maybe I broke the dormant flag handling?

Or maybe syzbot got here after the arptables bug has been hitted?

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Dmitry Vyukov]

On Thu, May 13, 2021 at 2:56 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> > Dmitry Vyukov <dvyukov@google.com> wrote:
> > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > >
> > > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > > during unregister"?
> > > The warning is the same, but the stack is different...
> >
> > No, this is a different bug.
> >
> > In both cases the caller attempts to unregister a hook that the core
> > can't find, but in this case the caller is nftables, not arptables.
>
> I see no reproducer for this bug. Maybe I broke the dormant flag handling?
>
> Or maybe syzbot got here after the arptables bug has been hitted?

syzbot always stops after the first bug to give you perfect "Not
tainted" oopses.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Pablo Neira Ayuso]

On Thu, May 13, 2021 at 09:08:20AM +0200, Dmitry Vyukov wrote:
> On Thu, May 13, 2021 at 2:56 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> >
> > On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> > > Dmitry Vyukov <dvyukov@google.com> wrote:
> > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > > >
> > > > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > > > during unregister"?
> > > > The warning is the same, but the stack is different...
> > >
> > > No, this is a different bug.
> > >
> > > In both cases the caller attempts to unregister a hook that the core
> > > can't find, but in this case the caller is nftables, not arptables.
> >
> > I see no reproducer for this bug. Maybe I broke the dormant flag handling?
> >
> > Or maybe syzbot got here after the arptables bug has been hitted?
> 
> syzbot always stops after the first bug to give you perfect "Not
> tainted" oopses.

Looking at the log file:

https://syzkaller.appspot.com/text?tag=CrashLog&x=110a3096d00000

This is mixing calls to nftables:

14:43:16 executing program 0:
r0 = socket$nl_netfilter(0x10, 0x3, 0xc)
sendmsg$NFT_BATCH(r0, &(0x7f000000c2c0)={0x0, 0x0, &(0x7f0000000000)={&(0x7f00000001c0)={{0x9}, [@NFT_MSG_NEWTABLE={0x28, 0x0, 0xa, 0x3, 0x0, 0x0, {0x2}, [@NFTA_TABLE_NAME={0x9, 0x1, 'syz0\x00'}, @NFTA_TABLE_FLAGS={0x8}]}], {0x14}}, 0x50}}, 0x0)

with arptables:

14:43:16 executing program 1:
r0 = socket$inet_udp(0x2, 0x2, 0x0)
setsockopt$ARPT_SO_SET_REPLACE(r0, 0x0, 0x60, &(0x7f0000000000)={'filter\x00', 0x4, 0x4, 0x3f8, 0x310, 0x200, 0x200, 0x310, 0x310, 0x310, 0x4, 0x0, {[{{@arp={@broadcast, @rand_addr, 0x87010000, 0x0, 0x0, 0x0, {@mac=@link_local}, {@mac}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'bridge0\x00', 'erspan0\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz1\x00', 0x0, 0x4}}}, {{@arp={@initdev={0xac, 0x1e, 0x0, 0x0}, @local, 0x0, 0x0, 0x0, 0x0, {@mac=@remote}, {}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_bridge\x00', 'geneve1\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz0\x00', 0x0, 0x2}}}, {{@arp={@local, @multicast1, 0x0, 0x0, 0x0, 0x0, {}, {@mac=@broadcast}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_batadv\x00', 'veth0_to_hsr\x00'}, 0xc0, 0x110}, @mangle={0x50, 'mangle\x00', 0x0, {@mac=@remote, @mac=@local, @multicast2, @initdev={0xac, 0x1e, 0x0, 0x0}}}}], {{[], 0xc0, 0xe8}, {0x28}}}}, 0x448)

arptables was buggy at the time this bug has been reported.

Am I understanding correctly the syzbot log?

I wonder if the (buggy) arptables removed the incorrect hook from
nftables, then nftables crashed on the same location when removing the
hook. I don't see a clear sequence for this to happen though.

Would it be possible to make syzbot exercise the NFT_MSG_NEWTABLE
codepath (with NFTA_TABLE_FLAGS) to check if the problem still
persists?

Thanks.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Dmitry Vyukov]

On Mon, May 17, 2021 at 12:57 PM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> > > > Dmitry Vyukov <dvyukov@google.com> wrote:
> > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > > > >
> > > > > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > > > > during unregister"?
> > > > > The warning is the same, but the stack is different...
> > > >
> > > > No, this is a different bug.
> > > >
> > > > In both cases the caller attempts to unregister a hook that the core
> > > > can't find, but in this case the caller is nftables, not arptables.
> > >
> > > I see no reproducer for this bug. Maybe I broke the dormant flag handling?
> > >
> > > Or maybe syzbot got here after the arptables bug has been hitted?
> >
> > syzbot always stops after the first bug to give you perfect "Not
> > tainted" oopses.
>
> Looking at the log file:
>
> https://syzkaller.appspot.com/text?tag=CrashLog&x=110a3096d00000
>
> This is mixing calls to nftables:
>
> 14:43:16 executing program 0:
> r0 = socket$nl_netfilter(0x10, 0x3, 0xc)
> sendmsg$NFT_BATCH(r0, &(0x7f000000c2c0)={0x0, 0x0, &(0x7f0000000000)={&(0x7f00000001c0)={{0x9}, [@NFT_MSG_NEWTABLE={0x28, 0x0, 0xa, 0x3, 0x0, 0x0, {0x2}, [@NFTA_TABLE_NAME={0x9, 0x1, 'syz0\x00'}, @NFTA_TABLE_FLAGS={0x8}]}], {0x14}}, 0x50}}, 0x0)
>
> with arptables:
>
> 14:43:16 executing program 1:
> r0 = socket$inet_udp(0x2, 0x2, 0x0)
> setsockopt$ARPT_SO_SET_REPLACE(r0, 0x0, 0x60, &(0x7f0000000000)={'filter\x00', 0x4, 0x4, 0x3f8, 0x310, 0x200, 0x200, 0x310, 0x310, 0x310, 0x4, 0x0, {[{{@arp={@broadcast, @rand_addr, 0x87010000, 0x0, 0x0, 0x0, {@mac=@link_local}, {@mac}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'bridge0\x00', 'erspan0\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz1\x00', 0x0, 0x4}}}, {{@arp={@initdev={0xac, 0x1e, 0x0, 0x0}, @local, 0x0, 0x0, 0x0, 0x0, {@mac=@remote}, {}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_bridge\x00', 'geneve1\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz0\x00', 0x0, 0x2}}}, {{@arp={@local, @multicast1, 0x0, 0x0, 0x0, 0x0, {}, {@mac=@broadcast}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_batadv\x00', 'veth0_to_hsr\x00'}, 0xc0, 0x110}, @mangle={0x50, 'mangle\x00', 0x0, {@mac=@remote, @mac=@local, @multicast2, @initdev={0xac, 0x1e, 0x0, 0x0}}}}], {{[], 0xc0, 0xe8}, {0x28}}}}, 0x448)
>
> arptables was buggy at the time this bug has been reported.
>
> Am I understanding correctly the syzbot log?
>
> I wonder if the (buggy) arptables removed the incorrect hook from
> nftables, then nftables crashed on the same location when removing the
> hook. I don't see a clear sequence for this to happen though.
>
> Would it be possible to make syzbot exercise the NFT_MSG_NEWTABLE
> codepath (with NFTA_TABLE_FLAGS) to check if the problem still
> persists?


This happened only once so far 40 days ago. So if you consider it
possible that it actually happened due to the arptables issue, I would
mark it as invalid (with "#syz invalid") and move on. If it ever
happens again, syzbot will notify, but then we know it happened with
the aprtables issue fixed.

This bug does not have a reproducer, so it's not possible to test this
exact scenario. It's possible to replay the whole log, but somehow
syzkaller wasn't able to retrigger it by replaying the log. I don't
think it's worth our time at this point.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[Pablo Neira Ayuso]

On Mon, May 17, 2021 at 02:42:41PM +0200, Dmitry Vyukov wrote:
> On Mon, May 17, 2021 at 12:57 PM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > > On Sat, May 08, 2021 at 04:46:57PM +0200, Florian Westphal wrote:
> > > > > Dmitry Vyukov <dvyukov@google.com> wrote:
> > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > > > > Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com
> > > > > >
> > > > > > Is this also fixed by "netfilter: arptables: use pernet ops struct
> > > > > > during unregister"?
> > > > > > The warning is the same, but the stack is different...
> > > > >
> > > > > No, this is a different bug.
> > > > >
> > > > > In both cases the caller attempts to unregister a hook that the core
> > > > > can't find, but in this case the caller is nftables, not arptables.
> > > >
> > > > I see no reproducer for this bug. Maybe I broke the dormant flag handling?
> > > >
> > > > Or maybe syzbot got here after the arptables bug has been hitted?
> > >
> > > syzbot always stops after the first bug to give you perfect "Not
> > > tainted" oopses.
> >
> > Looking at the log file:
> >
> > https://syzkaller.appspot.com/text?tag=CrashLog&x=110a3096d00000
> >
> > This is mixing calls to nftables:
> >
> > 14:43:16 executing program 0:
> > r0 = socket$nl_netfilter(0x10, 0x3, 0xc)
> > sendmsg$NFT_BATCH(r0, &(0x7f000000c2c0)={0x0, 0x0, &(0x7f0000000000)={&(0x7f00000001c0)={{0x9}, [@NFT_MSG_NEWTABLE={0x28, 0x0, 0xa, 0x3, 0x0, 0x0, {0x2}, [@NFTA_TABLE_NAME={0x9, 0x1, 'syz0\x00'}, @NFTA_TABLE_FLAGS={0x8}]}], {0x14}}, 0x50}}, 0x0)
> >
> > with arptables:
> >
> > 14:43:16 executing program 1:
> > r0 = socket$inet_udp(0x2, 0x2, 0x0)
> > setsockopt$ARPT_SO_SET_REPLACE(r0, 0x0, 0x60, &(0x7f0000000000)={'filter\x00', 0x4, 0x4, 0x3f8, 0x310, 0x200, 0x200, 0x310, 0x310, 0x310, 0x4, 0x0, {[{{@arp={@broadcast, @rand_addr, 0x87010000, 0x0, 0x0, 0x0, {@mac=@link_local}, {@mac}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'bridge0\x00', 'erspan0\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz1\x00', 0x0, 0x4}}}, {{@arp={@initdev={0xac, 0x1e, 0x0, 0x0}, @local, 0x0, 0x0, 0x0, 0x0, {@mac=@remote}, {}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_bridge\x00', 'geneve1\x00'}, 0xc0, 0x100}, @unspec=@RATEEST={0x40, 'RATEEST\x00', 0x0, {'syz0\x00', 0x0, 0x2}}}, {{@arp={@local, @multicast1, 0x0, 0x0, 0x0, 0x0, {}, {@mac=@broadcast}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 'veth0_to_batadv\x00', 'veth0_to_hsr\x00'}, 0xc0, 0x110}, @mangle={0x50, 'mangle\x00', 0x0, {@mac=@remote, @mac=@local, @multicast2, @initdev={0xac, 0x1e, 0x0, 0x0}}}}], {{[], 0xc0, 0xe8}, {0x28}}}}, 0x448)
> >
> > arptables was buggy at the time this bug has been reported.
> >
> > Am I understanding correctly the syzbot log?
> >
> > I wonder if the (buggy) arptables removed the incorrect hook from
> > nftables, then nftables crashed on the same location when removing the
> > hook. I don't see a clear sequence for this to happen though.
> >
> > Would it be possible to make syzbot exercise the NFT_MSG_NEWTABLE
> > codepath (with NFTA_TABLE_FLAGS) to check if the problem still
> > persists?
> 
> 
> This happened only once so far 40 days ago. So if you consider it
> possible that it actually happened due to the arptables issue, I would
> mark it as invalid (with "#syz invalid") and move on. If it ever
> happens again, syzbot will notify, but then we know it happened with
> the aprtables issue fixed.
> 
> This bug does not have a reproducer, so it's not possible to test this
> exact scenario. It's possible to replay the whole log, but somehow
> syzkaller wasn't able to retrigger it by replaying the log. I don't
> think it's worth our time at this point.

Thanks.

I found the root cause, I was getting confused by the arptables
report. I'll post a patch.

Re: [syzbot] WARNING in __nf_unregister_net_hook (4)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    02d5e016800d Merge tag 'sound-5.15-rc4' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160132c0b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9290a409049988d4
dashboard link: https://syzkaller.appspot.com/bug?extid=154bd5be532a63aa778b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1400bf0f300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=144eaf17300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+154bd5be532a63aa778b@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468 __nf_unregister_net_hook+0x4b1/0x600 net/netfilter/core.c:468
Modules linked in:
CPU: 0 PID: 2648 Comm: kworker/u4:6 Not tainted 5.15.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:__nf_unregister_net_hook+0x4b1/0x600 net/netfilter/core.c:468
Code: 00 00 00 e8 41 e9 16 fa 41 83 fc 05 74 5e e8 f6 e1 16 fa 44 89 e6 bf 05 00 00 00 e8 29 e9 16 fa e9 f5 fd ff ff e8 df e1 16 fa <0f> 0b 48 c7 c7 80 dd 17 8d e8 c1 a8 d7 01 e9 b1 fe ff ff 48 89 f7
RSP: 0018:ffffc9000b10f658 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888070c20b98 RCX: 0000000000000000
RDX: ffff888024aa9c80 RSI: ffffffff875f1991 RDI: 0000000000000003
RBP: 0000000000000005 R08: 0000000000000000 R09: ffffc9000b10f597
R10: ffffffff875f159f R11: 000000000000000e R12: 0000000000000001
R13: ffff88801d2b43d8 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f45ae09b0 CR3: 000000000b68e000 CR4: 0000000000350ef0
Call Trace:
 nf_unregister_net_hook+0xd5/0x110 net/netfilter/core.c:502
 nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline]
 nf_tables_unregister_hook.part.0+0x1ab/0x200 net/netfilter/nf_tables_api.c:273
 nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline]
 __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524
 nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline]
 nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1996
 call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
 call_netdevice_notifiers net/core/dev.c:2022 [inline]
 unregister_netdevice_many+0x951/0x1790 net/core/dev.c:11043
 ieee80211_remove_interfaces+0x394/0x820 net/mac80211/iface.c:2140
 ieee80211_unregister_hw+0x47/0x1f0 net/mac80211/main.c:1391
 mac80211_hwsim_del_radio drivers/net/wireless/mac80211_hwsim.c:3457 [inline]
 hwsim_exit_net+0x50e/0xca0 drivers/net/wireless/mac80211_hwsim.c:4217
 ops_exit_list+0xb0/0x160 net/core/net_namespace.c:168
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:591
 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295