INFO: task hung in lock_sock_nested

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syzbot

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May 8, 2020, 3:53:17 PM5/8/20
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Hello,

syzbot found the following crash on:

HEAD commit: 84920cc7 Linux 4.19.121
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=165c495c100000
kernel config: https://syzkaller.appspot.com/x/.config?x=1deab1e33c1e397b
dashboard link: https://syzkaller.appspot.com/bug?extid=24fcab5889ec30bab5d7
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+24fcab...@syzkaller.appspotmail.com

INFO: task syz-executor.3:30425 blocked for more than 140 seconds.
Not tainted 4.19.121-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D29872 30425 30423 0x00000000
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3559
__lock_sock+0x13d/0x260 net/core/sock.c:2318
lock_sock_nested+0xf1/0x110 net/core/sock.c:2843
lock_sock include/net/sock.h:1506 [inline]
ax25_accept+0x122/0x700 net/ax25/af_ax25.c:1346
__sys_accept4+0x322/0x5f0 net/socket.c:1589
sock: process `syz-executor.5' is using obsolete setsockopt SO_BSDCOMPAT
__do_sys_accept net/socket.c:1630 [inline]
__se_sys_accept net/socket.c:1627 [inline]
__x64_sys_accept+0x71/0xb0 net/socket.c:1627
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: Bad RIP value.
RSP: 002b:00007f1d89423c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002b
RAX: ffffffffffffffda RBX: 00000000004d8d60 RCX: 000000000045c829
RDX: 0000000020000080 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000006 R14: 00000000004c2a8d R15: 00007f1d894246d4

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
#0: 0000000015e54ef3 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
1 lock held by in:imklog/6178:
1 lock held by syz-executor.2/8841:
#0: 000000007f247898 (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:62 [inline]
#0: 000000007f247898 (&pipe->mutex/1){+.+.}, at: pipe_lock+0x63/0x80 fs/pipe.c:70
1 lock held by syz-executor.3/30160:
#0: 000000006ed8eb29 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 000000006ed8eb29 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/30423:
#0: 000000001c54f02a (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 000000001c54f02a (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/30490:
#0: 000000003fe41743 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 000000003fe41743 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/31404:
#0: 00000000183aed51 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 00000000183aed51 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/32202:
#0: 00000000903052f4 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 00000000903052f4 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/32387:
#0: 00000000677aab64 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 00000000677aab64 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/32498:
#0: 00000000250b389b (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 00000000250b389b (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/546:
#0: 000000002d3a4c9d (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 000000002d3a4c9d (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
1 lock held by syz-executor.3/653:
#0: 00000000630b5702 (sk_lock-AF_AX25){+.+.}, at: lock_sock include/net/sock.h:1506 [inline]
#0: 00000000630b5702 (sk_lock-AF_AX25){+.+.}, at: ax25_recvmsg+0xbb/0x810 net/ax25/af_ax25.c:1621
2 locks held by kworker/0:2/2471:
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: 0000000028be9c1f ((wq_completion)"rcu_gp"){+.+.}, at: process_one_work+0x81a/0x1640 kernel/workqueue.c:2126
#1: 000000006602e3b4 ((work_completion)(&rew.rew_work)){+.+.}, at: process_one_work+0x84e/0x1640 kernel/workqueue.c:2130
1 lock held by syz-executor.0/3016:
#0: 000000007cfb57e4 (rtnl_mutex){+.+.}, at: sock_do_ioctl+0x24e/0x2f0 net/socket.c:963
2 locks held by syz-executor.3/2955:
#0: 000000007cfb57e4 (rtnl_mutex){+.+.}, at: ppp_release+0x11d/0x1e0 drivers/net/ppp/ppp_generic.c:407
#1: 000000003ef44820 (rcu_preempt_state.exp_mutex){+.+.}, at: exp_funnel_lock kernel/rcu/tree_exp.h:297 [inline]
#1: 000000003ef44820 (rcu_preempt_state.exp_mutex){+.+.}, at: _synchronize_rcu_expedited+0x54d/0x750 kernel/rcu/tree_exp.h:667

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

NMI backtrace for cpu 0
CPU: 0 PID: 1079 Comm: khungtaskd Not tainted 4.19.121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x962/0xe40 kernel/hung_task.c:287
kthread+0x34a/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 3690 Comm: systemd-journal Not tainted 4.19.121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:779 [inline]
RIP: 0010:debug_check_no_obj_freed+0x104/0x42e lib/debugobjects.c:817
Code: 4c 8b 28 4d 85 ed 0f 84 2a 02 00 00 31 db 4c 89 e8 48 c1 e8 03 80 3c 28 00 0f 85 40 02 00 00 49 8d 7d 18 83 c3 01 4d 8b 7d 00 <48> 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 31 02 00 00 49 8b 45 18 48
RSP: 0018:ffff888093e1fb90 EFLAGS: 00000006
RAX: 1ffff110118f1a54 RBX: 0000000000000003 RCX: ffffffff8150969b
RDX: 1ffffffff1742f2b RSI: 0000000000000004 RDI: ffff88808c78d2b8
RBP: dffffc0000000000 R08: 0000000000007dc2 R09: fffffbfff1742f2a
R10: fffffbfff1742f29 R11: ffffffff8ba1794b R12: 0000000000000082
R13: ffff88808c78d2a0 R14: ffffffff8ba17948 R15: ffff88808886ac40
FS: 00007f40f34dd8c0(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f40f0b29000 CR3: 0000000094263000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
free_pages_prepare mm/page_alloc.c:1055 [inline]
__free_pages_ok+0x241/0xd80 mm/page_alloc.c:1273
slab_destroy+0x1f/0x50 mm/slab.c:1713
slabs_destroy+0x6a/0x90 mm/slab.c:1729
cache_flusharray mm/slab.c:3490 [inline]
___cache_free+0x277/0x380 mm/slab.c:3532
qlink_free mm/kasan/quarantine.c:147 [inline]
qlist_free_all+0x79/0x140 mm/kasan/quarantine.c:166
quarantine_reduce+0x164/0x1a0 mm/kasan/quarantine.c:259
kasan_kmalloc+0x95/0xe0 mm/kasan/kasan.c:538
slab_post_alloc_hook mm/slab.h:445 [inline]
slab_alloc mm/slab.c:3397 [inline]
kmem_cache_alloc+0x114/0x710 mm/slab.c:3557
prepare_creds+0x39/0x410 kernel/cred.c:255
do_faccessat+0x94/0x7a0 fs/open.c:359
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f40f27999c7
Code: 83 c4 08 48 3d 01 f0 ff ff 73 01 c3 48 8b 0d c8 d4 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 15 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a1 d4 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffdbc83f628 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00007ffdbc842540 RCX: 00007f40f27999c7
RDX: 00007f40f320aa00 RSI: 0000000000000000 RDI: 000055e7c60c59a3
RBP: 00007ffdbc83f660 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000069 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ffdbc842540 R15: 00007ffdbc83fb50


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot

unread,
Sep 5, 2020, 3:53:15 PM9/5/20
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
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