[syzbot ci] Re: netfilter: nfnetlink_queue: optimize verdict lookup with hash table

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syzbot ci

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Nov 13, 2025, 8:50:52 AM (2 days ago) Nov 13
to core...@netfilter.org, da...@davemloft.net, edum...@google.com, f...@strlen.de, ho...@kernel.org, kad...@netfilter.org, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, netfilt...@vger.kernel.org, pab...@redhat.com, pa...@netfilter.org, ph...@nwl.cc, scott.k...@gmail.com, scott_m...@apple.com, syz...@lists.linux.dev, syzkall...@googlegroups.com
syzbot ci has tested the following series

[v2] netfilter: nfnetlink_queue: optimize verdict lookup with hash table
https://lore.kernel.org/all/20251113092606.914...@apple.com
* [PATCH v2] netfilter: nfnetlink_queue: optimize verdict lookup with hash table

and found the following issue:
BUG: sleeping function called from invalid context in instance_create

Full report is available here:
https://ci.syzbot.org/series/001a6a6c-7e1b-46e8-995d-5b6d650af320

***

BUG: sleeping function called from invalid context in instance_create

tree: nf-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/netfilter/nf-next.git
base: 0d0eb186421d0886ac466008235f6d9eedaf918e
arch: amd64
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config: https://ci.syzbot.org/builds/69a4254b-f4aa-45a7-a4bd-2d23940887f3/config
C repro: https://ci.syzbot.org/findings/8074062c-0aee-4734-a3d1-587b80676bf1/c_repro
syz repro: https://ci.syzbot.org/findings/8074062c-0aee-4734-a3d1-587b80676bf1/syz_repro

netlink: 'syz.0.17': attribute type 6 has an invalid length.
BUG: sleeping function called from invalid context at ./include/linux/sched/mm.h:321
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5968, name: syz.0.17
preempt_count: 1, expected: 0
RCU nest depth: 1, expected: 0
3 locks held by syz.0.17/5968:
#0: ffffffff99cc1c30 (nfnl_subsys_queue){+.+.}-{4:4}, at: nfnl_lock net/netfilter/nfnetlink.c:98 [inline]
#0: ffffffff99cc1c30 (nfnl_subsys_queue){+.+.}-{4:4}, at: nfnetlink_rcv_msg+0x9dc/0x1130 net/netfilter/nfnetlink.c:295
#1: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#1: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#1: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: nfqnl_recv_config+0x222/0xf90 net/netfilter/nfnetlink_queue.c:1653
#2: ffff888112297d18 (&q->instances_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#2: ffff888112297d18 (&q->instances_lock){+.+.}-{3:3}, at: instance_create+0x121/0x740 net/netfilter/nfnetlink_queue.c:206
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 UID: 0 PID: 5968 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
__might_resched+0x495/0x610 kernel/sched/core.c:8927
might_alloc include/linux/sched/mm.h:321 [inline]
slab_pre_alloc_hook mm/slub.c:4913 [inline]
slab_alloc_node mm/slub.c:5248 [inline]
__do_kmalloc_node mm/slub.c:5633 [inline]
__kvmalloc_node_noprof+0x149/0x910 mm/slub.c:7089
kvmalloc_array_node_noprof include/linux/slab.h:1122 [inline]
instance_create+0x203/0x740 net/netfilter/nfnetlink_queue.c:218
nfqnl_recv_config+0x660/0xf90 net/netfilter/nfnetlink_queue.c:1667
nfnetlink_rcv_msg+0xb4d/0x1130 net/netfilter/nfnetlink.c:302
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2550
nfnetlink_rcv+0x282/0x2590 net/netfilter/nfnetlink.c:669
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: 0033:0x7f7a65f8f6c9
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:00007ffde4361588 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7a661e5fa0 RCX: 00007f7a65f8f6c9
RDX: 0000000000008010 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007f7a66011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7a661e5fa0 R14: 00007f7a661e5fa0 R15: 0000000000000003
</TASK>


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzk...@googlegroups.com.
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