[v5.15] possible deadlock in vmci_qp_broker_detach

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d98fd109f827 Linux 5.15.172
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15ba9b5f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=106da063d1125aa0
dashboard link: https://syzkaller.appspot.com/bug?extid=0c684198271115ab86bc
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13ef92c0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d480511ac07d/disk-d98fd109.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/743b2602e9fd/vmlinux-d98fd109.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c93fe25414b0/bzImage-d98fd109.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0c6841...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
5.15.172-syzkaller #0 Not tainted
--------------------------------------------
syz.1.11633/28647 is trying to acquire lock:
ffffffff8d138638 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0xf1/0x1210 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

but task is already holding lock:
ffffffff8d138638 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0xf1/0x1210 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(qp_broker_list.mutex);
lock(qp_broker_list.mutex);

*** DEADLOCK ***

May be due to missing lock nesting notation

1 lock held by syz.1.11633/28647:
#0: ffffffff8d138638 (qp_broker_list.mutex){+.+.}-{3:3}, at: vmci_qp_broker_detach+0xf1/0x1210 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095

stack backtrace:
CPU: 1 PID: 28647 Comm: syz.1.11633 Not tainted 5.15.172-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
print_deadlock_bug kernel/locking/lockdep.c:2946 [inline]
check_deadlock kernel/locking/lockdep.c:2989 [inline]
validate_chain+0x46d2/0x5930 kernel/locking/lockdep.c:3775
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
vmci_qp_broker_detach+0xf1/0x1210 drivers/misc/vmw_vmci/vmci_queue_pair.c:2095
ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:444 [inline]
kref_put include/linux/kref.h:65 [inline]
vmci_ctx_put+0x7bf/0xe30 drivers/misc/vmw_vmci/vmci_context.c:497
vmci_ctx_enqueue_datagram+0x38e/0x430 drivers/misc/vmw_vmci/vmci_context.c:360
dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:276 [inline]
vmci_datagram_dispatch+0x43d/0xc10 drivers/misc/vmw_vmci/vmci_datagram.c:340
qp_notify_peer drivers/misc/vmw_vmci/vmci_queue_pair.c:1481 [inline]
vmci_qp_broker_detach+0xb54/0x1210 drivers/misc/vmw_vmci/vmci_queue_pair.c:2188
ctx_free_ctx drivers/misc/vmw_vmci/vmci_context.c:444 [inline]
kref_put include/linux/kref.h:65 [inline]
vmci_ctx_put+0x7bf/0xe30 drivers/misc/vmw_vmci/vmci_context.c:497
vmci_host_close+0x97/0x160 drivers/misc/vmw_vmci/vmci_host.c:143
__fput+0x3fe/0x8e0 fs/file_table.c:280
task_work_run+0x129/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f19a0f7f719
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:00007ffe2eb49d78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000053a71 RCX: 00007f19a0f7f719
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f19a1138a80 R08: 0000000000000001 R09: 00007ffe2eb4a06f
R10: 00007f19a0e01000 R11: 0000000000000246 R12: 0000000000053ab5
R13: 00007ffe2eb49e80 R14: 0000000000000032 R15: ffffffffffffffff
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.