[moderation] [lsm?] [net?] WARNING: lock held when returning to user space in netlbl_conn_setattr

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bb1556ec9464 Merge tag 'linux-watchdog-6.16-rc1' of git://..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=140acc82580000
kernel config: https://syzkaller.appspot.com/x/.config?x=577ec106a16bf15a
dashboard link: https://syzkaller.appspot.com/bug?extid=1a906a185ae55c852793
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [da...@davemloft.net edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org linux-secu...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com pa...@paul-moore.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4be175521d40/disk-bb1556ec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0daf186984ce/vmlinux-bb1556ec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5a371f9e8ed9/bzImage-bb1556ec.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1a906a...@syzkaller.appspotmail.com

================================================
WARNING: lock held when returning to user space!
6.15.0-syzkaller-10815-gbb1556ec9464 #0 Not tainted
------------------------------------------------
syz.4.1656/12100 is leaving the kernel with locks still held!
1 lock held by syz.4.1656/12100:
#0: ffffffff8e5c4d80 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e5c4d80 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8e5c4d80 (rcu_read_lock){....}-{1:3}, at: netlbl_conn_setattr+0x35/0x610 net/netlabel/netlabel_kapi.c:1140
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: CPU: 1 PID: 12100 at kernel/rcu/tree_plugin.h:332 rcu_note_context_switch+0xccc/0x1e00 kernel/rcu/tree_plugin.h:332
Modules linked in:
CPU: 1 UID: 0 PID: 12100 Comm: syz.4.1656 Not tainted 6.15.0-syzkaller-10815-gbb1556ec9464 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:rcu_note_context_switch+0xccc/0x1e00 kernel/rcu/tree_plugin.h:332
Code: 24 30 4c 8b 54 24 28 4c 8b 44 24 20 8b 4c 24 08 e9 cc 03 00 00 c6 05 6f 2a ed 0e 01 90 48 c7 c7 20 f2 ae 8b e8 55 f1 d7 ff 90 <0f> 0b 90 90 e9 35 f4 ff ff 38 d0 7f 08 84 c0 0f 85 10 09 00 00 80
RSP: 0000:ffffc90003a9fcc0 EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffff8880b853cc40 RCX: ffffc9000d01e000
RDX: 0000000000080000 RSI: ffffffff817ad375 RDI: 0000000000000001
RBP: ffff888030eda440 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888030eda440 R14: ffffffff90a7e544 R15: ffff8880b853bc40
FS: 00007f3d8bc116c0(0000) GS:ffff888124865000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000192030 CR3: 000000005831a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__schedule+0x2f7/0x5de0 kernel/sched/core.c:6686
__schedule_loop kernel/sched/core.c:6859 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:6874
exit_to_user_mode_loop kernel/entry/common.c:102 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
irqentry_exit_to_user_mode+0xcf/0x270 kernel/entry/common.c:184
asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
RIP: 0033:0x7f3d8ad8e969
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:00007f3d8bc11038 EFLAGS: 00000246
RAX: ffffffffffffff9f RBX: 00007f3d8afb5fa0 RCX: 00007f3d8ad8e969
RDX: 000000000000006f RSI: 0000000000000084 RDI: 0000000000000003
RBP: 00007f3d8ae10ab1 R08: 0000200000000380 R09: 0000000000000000
R10: 0000200000000340 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f3d8afb5fa0 R15: 00007ffc01de6168
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.