syzbot


INFO: task hung in __flush_work

Status: fixed on 2020/08/12 22:58
Reported-by: syzbot+1000508396c783108d91@syzkaller.appspotmail.com
Fix commit: af224c2eeda2 net/9p: validate fds in p9_fd_open
First crash: 2043d, last: 1594d
Fix bisection: fixed by (bisect log) :
commit af224c2eeda2bd6679355f588766c5a8da8920a2
Author: Christoph Hellwig <hch@lst.de>
Date: Fri Jul 10 08:57:22 2020 +0000

  net/9p: validate fds in p9_fd_open

  
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in __flush_work net C done error 1440 1652d 2107d 0/28 auto-obsoleted due to no activity on 2022/12/27 22:33
Fix bisection attempts (9)
Created Duration User Patch Repo Result
2020/08/12 18:47 4h06m bisect fix linux-4.19.y OK (1) job log
2020/07/13 15:46 30m bisect fix linux-4.19.y OK (0) job log log
2020/06/13 13:38 28m bisect fix linux-4.19.y OK (0) job log log
2020/05/14 13:06 31m bisect fix linux-4.19.y OK (0) job log log
2020/04/14 12:37 29m bisect fix linux-4.19.y OK (0) job log log
2020/03/15 10:56 32m bisect fix linux-4.19.y OK (0) job log log
2020/02/14 10:24 31m bisect fix linux-4.19.y OK (0) job log log
2020/01/15 09:51 30m bisect fix linux-4.19.y OK (0) job log log
2019/12/16 08:34 32m bisect fix linux-4.19.y OK (0) job log log

Sample crash report:
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
audit: type=1400 audit(1555836799.478:38): avc:  denied  { associate } for  pid=7996 comm="syz-executor.0" name="syz0" scontext=unconfined_u:object_r:unlabeled_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
INFO: task syz-executor.0:8302 blocked for more than 140 seconds.
      Not tainted 4.19.36 #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28504  8302   7996 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x813/0x1d00 kernel/sched/core.c:3474
 schedule+0x92/0x1c0 kernel/sched/core.c:3518
 schedule_timeout+0x8ca/0xfd0 kernel/time/timer.c:1780
 do_wait_for_common kernel/sched/completion.c:83 [inline]
 __wait_for_common kernel/sched/completion.c:104 [inline]
 wait_for_common kernel/sched/completion.c:115 [inline]
 wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136
 __flush_work+0x474/0x840 kernel/workqueue.c:2917
 __cancel_work_timer+0x3bf/0x520 kernel/workqueue.c:3004
 cancel_work_sync+0x18/0x20 kernel/workqueue.c:3040
 p9_conn_destroy net/9p/trans_fd.c:864 [inline]
 p9_fd_close+0x2b7/0x470 net/9p/trans_fd.c:891
 p9_client_create+0x9c5/0x12e0 net/9p/client.c:1086
 v9fs_session_init+0x1e7/0x18d0 fs/9p/v9fs.c:421
 v9fs_mount+0x7d/0x920 fs/9p/vfs_super.c:135
 mount_fs+0xae/0x331 fs/super.c:1261
 vfs_kern_mount.part.0+0x6f/0x410 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 do_new_mount fs/namespace.c:2469 [inline]
 do_mount+0x53e/0x2bc0 fs/namespace.c:2799
 ksys_mount+0xdb/0x150 fs/namespace.c:3015
 __do_sys_mount fs/namespace.c:3029 [inline]
 __se_sys_mount fs/namespace.c:3026 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3026
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c29
Code: 08 48 c7 44 24 10 04 00 00 00 e8 62 d8 fa ff 48 8b 44 24 18 48 8b 4c 24 30 48 83 c1 08 48 89 0c 24 48 89 44 24 08 48 c7 44 24 <10> 10 00 00 00 e8 3d d8 fa ff 48 8b 44 24 18 48 89 44 24 40 48 8b
RSP: 002b:00007f7b928bac78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458c29
RDX: 0000000020000100 RSI: 00000000200000c0 RDI: 0000000000000000
RBP: 000000000073bf00 R08: 0000000020000140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7b928bb6d4
R13: 00000000004c4c14 R14: 00000000004d88a0 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1027:
 #0: 0000000077c0cb21 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438
2 locks held by kworker/1:2/2710:
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: 000000009405ed2f ((wq_completion)"events"){+.+.}, at: process_one_work+0x87e/0x1760 kernel/workqueue.c:2124
 #1: 00000000170ff86c ((work_completion)(&m->rq)){+.+.}, at: process_one_work+0x8b4/0x1760 kernel/workqueue.c:2128
1 lock held by rsyslogd/7832:
 #0: 000000003d030570 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767
2 locks held by getty/7953:
 #0: 00000000bbc6053a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 000000003402ee32 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7954:
 #0: 0000000098e436f9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 0000000049a1c156 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7955:
 #0: 00000000635a8a7f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 0000000083602d88 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7956:
 #0: 0000000043d31f9e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 00000000cdb56a82 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7957:
 #0: 000000008491a118 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 00000000c0e44665 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7958:
 #0: 00000000435de401 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 00000000770604d2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154
2 locks held by getty/7959:
 #0: 000000002d19a28b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:363
 #1: 000000002426230d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b30 drivers/tty/n_tty.c:2154

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

NMI backtrace for cpu 0
CPU: 0 PID: 1027 Comm: khungtaskd Not tainted 4.19.36 #4
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+0x172/0x1f0 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0x9df/0xee0 kernel/hung_task.c:287
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/04/21 09:06 linux-4.19.y c98875d930e9 b0e8efcb .config console log report syz ci2-linux-4-19
2019/07/31 04:03 linux-4.19.y 64f4694072aa 7c7ded69 .config console log report ci2-linux-4-19
2019/07/21 20:47 linux-4.19.y be9b6782a9eb 1656845f .config console log report ci2-linux-4-19
2019/06/07 07:48 linux-4.19.y e109a984cf38 698773cb .config console log report ci2-linux-4-19
2019/06/06 08:48 linux-4.19.y e109a984cf38 a547defc .config console log report ci2-linux-4-19
2019/05/02 21:28 linux-4.19.y a03957ab0fd5 e9039493 .config console log report ci2-linux-4-19
* Struck through repros no longer work on HEAD.