INFO: task hung in __loop_clr_fd

From: Hao Sun
Date: Wed Nov 17 2021 - 20:11:13 EST

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Hello,

When using Healer to fuzz the latest Linux kernel, the following crash
was triggered.

HEAD commit: 8ab774587903 Merge tag 'trace-v5.16-5'
git tree: upstream
console output: https://paste.ubuntu.com/p/hjFJMh2mcT/plain/
kernel config: https://paste.ubuntu.com/p/cFf8tS9V8w/plain/
C reproducer: https://paste.ubuntu.com/p/hyHTmH5JtP/plain/
Syzlang reproducer: https://paste.ubuntu.com/p/GqttBp86F8/plain/

If you fix this issue, please add the following tag to the commit:
Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>

INFO: task syz-executor:7502 blocked for more than 143 seconds.
Not tainted 5.16.0-rc1+ #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:24440 pid: 7502 ppid: 6632 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:4972 [inline]
__schedule+0xcd9/0x2530 kernel/sched/core.c:6253
schedule+0xd2/0x260 kernel/sched/core.c:6326
blk_mq_freeze_queue_wait+0x112/0x160 block/blk-mq.c:178
__loop_clr_fd+0x1ae/0x1080 drivers/block/loop.c:1122
loop_clr_fd drivers/block/loop.c:1237 [inline]
lo_ioctl+0x398/0x1680 drivers/block/loop.c:1562
blkdev_ioctl+0x37a/0x800 block/ioctl.c:609
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f41609fb9db
RSP: 002b:00007f415df63a68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000020000180 RCX: 00007f41609fb9db
RDX: 0000000000000000 RSI: 0000000000004c01 RDI: 0000000000000006
RBP: 00007f415df646bc R08: 00007f415df63b00 R09: 0000000020000100
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000016 R14: 00007f415df63ac0 R15: 0000000020000680
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/39:
#0: ffffffff8bb80a60 (rcu_read_lock){....}-{1:2}, at:
debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458
1 lock held by in:imklog/6333:
#0: ffff88810634e170 (&f->f_pos_lock){+.+.}-{3:3}, at:
__fdget_pos+0xe9/0x100 fs/file.c:990
1 lock held by syz-executor/7502:
#0: ffff8880198ccb60 (&lo->lo_mutex){+.+.}-{3:3}, at:
__loop_clr_fd+0x7a/0x1080 drivers/block/loop.c:1106
2 locks held by syz-executor/9352:
#0: ffff8880198d9118 (&disk->open_mutex){+.+.}-{3:3}, at:
blkdev_get_by_dev block/bdev.c:819 [inline]
#0: ffff8880198d9118 (&disk->open_mutex){+.+.}-{3:3}, at:
blkdev_get_by_dev+0x39a/0x8d0 block/bdev.c:792
#1: ffff8880198ccb60 (&lo->lo_mutex){+.+.}-{3:3}, at:
lo_open+0x75/0x120 drivers/block/loop.c:1733

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 39 Comm: khungtaskd Not tainted 5.16.0-rc1+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1e1/0x220 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xcc8/0x1010 kernel/hung_task.c:295
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 0 to CPUs 1-3:
NMI backtrace for cpu 2
CPU: 2 PID: 7532 Comm: kworker/u8:3 Not tainted 5.16.0-rc1+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Workqueue: bat_events batadv_nc_worker
RIP: 0010:debug_lockdep_rcu_enabled+0x23/0x30 kernel/rcu/update.c:280
Code: cc cc cc cc cc cc cc 8b 05 7a ae 41 04 85 c0 74 21 8b 05 ac e1
41 04 85 c0 74 17 65 48 8b 04 25 40 70 02 00 8b 80 1c 0a 00 00 <85> c0
0f 94 c0 0f b6 c0 c3 cc cc cc cc 41 54 55 48 c7 c5 50 aa 03
RSP: 0018:ffffc900080cfb90 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffc900080cfbc8 RCX: ffffffff815c72b1
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffc900080cfbc8
RBP: 1ffff92001019f85 R08: ffffffff88eba16a R09: fffffbfff1b210c3
R10: ffffffff8d908617 R11: fffffbfff1b210c2 R12: ffffffff8bb80a60
R13: 0000000000000048 R14: dffffc0000000000 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888063f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558c721da758 CR3: 0000000106d0a000 CR4: 0000000000350ee0
Call Trace:
<TASK>
rcu_read_lock_held_common+0x9/0x90 kernel/rcu/update.c:104
rcu_read_lock_sched_held+0x5a/0xd0 kernel/rcu/update.c:123
trace_lock_release include/trace/events/lock.h:58 [inline]
lock_release+0x4e6/0x670 kernel/locking/lockdep.c:5648
rcu_lock_release include/linux/rcupdate.h:273 [inline]
rcu_read_unlock include/linux/rcupdate.h:721 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
batadv_nc_worker+0x1dd/0x770 net/batman-adv/network-coding.c:723
process_one_work+0x9df/0x16d0 kernel/workqueue.c:2298
worker_thread+0x90/0xed0 kernel/workqueue.c:2445
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
NMI backtrace for cpu 3 skipped: idling at native_safe_halt
arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 3 skipped: idling at arch_safe_halt
arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 3 skipped: idling at default_idle+0xb/0x10
arch/x86/kernel/process.c:733
NMI backtrace for cpu 1
CPU: 1 PID: 3045 Comm: systemd-journal Not tainted 5.16.0-rc1+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:__lock_acquire+0x198/0x57e0 kernel/locking/lockdep.c:4930
Code: 90 83 e2 07 83 c2 03 89 44 24 18 40 38 f2 7c 09 40 84 f6 0f 85
97 14 00 00 44 8b 25 b2 e8 ef 0e 45 85 e4 75 0b 83 7c 24 18 2f <0f> 87
b8 12 00 00 49 8d bd 20 0a 00 00 48 81 eb 60 1d f7 8f 48 b8
RSP: 0018:ffffc900012dfac0 EFLAGS: 00000097
RAX: 0000000000000000 RBX: ffffffff8ff7bea0 RCX: 0000000000000000
RDX: 0000000000000003 RSI: 0000000000000004 RDI: ffff88801b07ede0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff8d908617 R11: fffffbfff1b210c2 R12: 0000000000000000
R13: ffff888016d18000 R14: ffff88801b07edd8 R15: 0000000000000000
FS: 00007f28184058c0(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f281578e050 CR3: 000000001b577000 CR4: 0000000000350ee0
Call Trace:
<TASK>
lock_acquire kernel/locking/lockdep.c:5637 [inline]
lock_acquire+0x1ab/0x520 kernel/locking/lockdep.c:5602
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:349 [inline]
alloc_fd+0x6e/0x660 fs/file.c:477
do_sys_openat2+0x490/0x9a0 fs/open.c:1210
do_sys_open+0xc3/0x140 fs/open.c:1228
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2817995840
Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66
0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24
RSP: 002b:00007ffd65ddf8f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffd65ddfc00 RCX: 00007f2817995840
RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 0000557a9fff42a0
RBP: 000000000000000d R08: 000000000000ffc0 R09: 00000000ffffffff
R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000557a9ffe9040 R14: 00007ffd65ddfbc0 R15: 0000557a9fff5a20
</TASK>
----------------
Code disassembly (best guess):
0: cc int3
1: cc int3
2: cc int3
3: cc int3
4: cc int3
5: cc int3
6: cc int3
7: 8b 05 7a ae 41 04 mov 0x441ae7a(%rip),%eax # 0x441ae87
d: 85 c0 test %eax,%eax
f: 74 21 je 0x32
11: 8b 05 ac e1 41 04 mov 0x441e1ac(%rip),%eax # 0x441e1c3
17: 85 c0 test %eax,%eax
19: 74 17 je 0x32
1b: 65 48 8b 04 25 40 70 mov %gs:0x27040,%rax
22: 02 00
24: 8b 80 1c 0a 00 00 mov 0xa1c(%rax),%eax
* 2a: 85 c0 test %eax,%eax <-- trapping instruction
2c: 0f 94 c0 sete %al
2f: 0f b6 c0 movzbl %al,%eax
32: c3 retq
33: cc int3
34: cc int3
35: cc int3
36: cc int3
37: 41 54 push %r12
39: 55 push %rbp
3a: 48 rex.W
3b: c7 .byte 0xc7
3c: c5 50 aa (bad)
3f: 03 .byte 0x3

Next message: Linus Torvalds: "Re: [REGRESSION] 5.16rc1: SA_IMMUTABLE breaks debuggers"
Previous message: zhenggy: "Re: [PATCH] ipvs: remove unused variable for ip_vs_new_dest"
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