syzbot


INFO: task hung in fb_open

Status: upstream: reported C repro on 2019/12/03 09:19
Reported-by: syzbot+49e4beaefa2981579752@syzkaller.appspotmail.com
First crash: 938d, last: 641d

Fix bisection: failed (bisect log)
similar bugs (4):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in fb_open C done 552 683d 937d 0/22 closed as dup on 2020/07/27 23:07
linux-4.19 INFO: task hung in fb_open (2) 1 477d 477d 0/1 auto-closed as invalid on 2021/07/05 14:58
linux-4.19 INFO: task hung in fb_open 108 699d 936d 0/1 auto-closed as invalid on 2020/11/26 05:30
upstream INFO: task hung in fb_open (2) 2 641d 641d 0/22 auto-closed as invalid on 2020/12/23 12:44

Sample crash report:
audit: type=1400 audit(1575360785.721:36): avc:  denied  { map } for  pid=6986 comm="syz-executor833" path="/root/syz-executor833830099" dev="sda1" ino=1426 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
INFO: task syz-executor833:6988 blocked for more than 140 seconds.
      Not tainted 4.14.157-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor833 D28904  6988   6984 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 fb_open+0xb7/0x420 drivers/video/fbdev/core/fbmem.c:1468
 chrdev_open+0x207/0x590 fs/char_dev.c:423
 do_dentry_open+0x73b/0xeb0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:891
 do_last fs/namei.c:3425 [inline]
 path_openat+0x8bd/0x3f70 fs/namei.c:3566
 do_filp_open+0x18e/0x250 fs/namei.c:3600
 do_sys_open+0x2c5/0x430 fs/open.c:1084
 SYSC_openat fs/open.c:1111 [inline]
 SyS_openat+0x30/0x40 fs/open.c:1105
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x445979
RSP: 002b:00007fdb83cc7db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00000000006dac38 RCX: 0000000000445979
RDX: 0000000000000000 RSI: 0000000020000280 RDI: ffffffffffffff9c
RBP: 00000000006dac30 R08: 00007fdb83cc8700 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac3c
R13: 00007ffed720031f R14: 00007fdb83cc89c0 R15: 20c49ba5e353f7cf
INFO: task syz-executor833:6989 blocked for more than 140 seconds.
      Not tainted 4.14.157-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor833 D29664  6989   6984 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
 schedule+0x92/0x1c0 kernel/sched/core.c:3428
 schedule_timeout+0x93b/0xe10 kernel/time/timer.c:1723
 __down_common kernel/locking/semaphore.c:221 [inline]
 __down+0x160/0x290 kernel/locking/semaphore.c:238
 down+0x64/0x90 kernel/locking/semaphore.c:62
 console_lock+0x28/0x80 kernel/printk/printk.c:2216
 do_fb_ioctl+0x36a/0x940 drivers/video/fbdev/core/fbmem.c:1121
 fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x445979
RSP: 002b:00007fdb83ca6db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dac48 RCX: 0000000000445979
RDX: 00000000200003c0 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000006dac40 R08: 00007fdb83ca7700 R09: 0000000000000000
R10: 00007fdb83ca7700 R11: 0000000000000246 R12: 00000000006dac4c
R13: 00007ffed720031f R14: 00007fdb83ca79c0 R15: 20c49ba5e353f7cf

Showing all locks held in the system:
1 lock held by khungtaskd/1042:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8148a428>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
1 lock held by rsyslogd/6840:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff8196407b>] __fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/6963:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6964:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6965:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6966:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6967:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6968:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
2 locks held by getty/6969:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff86614193>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8348e086>] n_tty_read+0x1e6/0x17b0 drivers/tty/n_tty.c:2156
1 lock held by syz-executor833/6988:
 #0:  (&fb_info->lock){+.+.}, at: [<ffffffff83246fd7>] fb_open+0xb7/0x420 drivers/video/fbdev/core/fbmem.c:1468

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

NMI backtrace for cpu 1
CPU: 1 PID: 1042 Comm: khungtaskd Not tainted 4.14.157-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5e7/0xb90 kernel/hung_task.c:274
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6987 Comm: syz-executor833 Not tainted 4.14.157-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888091f26640 task.stack: ffff88808bd48000
RIP: 0010:__writeq arch/x86/include/asm/io.h:100 [inline]
RIP: 0010:bitfill_aligned drivers/video/fbdev/core/cfbfillrect.c:64 [inline]
RIP: 0010:bitfill_aligned+0xdc/0x190 drivers/video/fbdev/core/cfbfillrect.c:35
RSP: 0018:ffff88808bd4f270 EFLAGS: 00000297
RAX: ffff888091f26640 RBX: 0000000000000050 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8880000a0000 RDI: 0000000000000040
RBP: ffff88808bd4f2a8 R08: 0000000000001400 R09: 0000000000000040
R10: ffffed104323b3b3 R11: ffff8882191d9d9f R12: ffff8880000a0280
R13: 0000000000000000 R14: ffff8880000a0140 R15: 0000000000000000
FS:  00007fdb83ce9700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdb83ca6e78 CR3: 00000000a0858000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 cfb_fillrect+0x3d0/0x720 drivers/video/fbdev/core/cfbfillrect.c:327
 vga16fb_fillrect+0x618/0x1880 drivers/video/fbdev/vga16fb.c:951
 bit_clear_margins+0x2d5/0x4f0 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x292/0x320 drivers/video/fbdev/core/fbcon.c:1317
 fbcon_switch+0xd38/0x1820 drivers/video/fbdev/core/fbcon.c:2299
 redraw_screen+0x335/0x7c0 drivers/tty/vt/vt.c:688
 fbcon_modechanged+0x59e/0x880 drivers/video/fbdev/core/fbcon.c:2946
 fbcon_event_notify+0x11f/0x17af drivers/video/fbdev/core/fbcon.c:3299
 notifier_call_chain+0x111/0x1b0 kernel/notifier.c:93
 __blocking_notifier_call_chain kernel/notifier.c:317 [inline]
 __blocking_notifier_call_chain kernel/notifier.c:304 [inline]
 blocking_notifier_call_chain kernel/notifier.c:328 [inline]
 blocking_notifier_call_chain+0x80/0xa0 kernel/notifier.c:325
 fb_notifier_call_chain+0x25/0x30 drivers/video/fbdev/core/fb_notify.c:45
 fb_set_var+0xb09/0xcf0 drivers/video/fbdev/core/fbmem.c:1054
 do_fb_ioctl+0x3cc/0x940 drivers/video/fbdev/core/fbmem.c:1127
 fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1242
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x445979
RSP: 002b:00007fdb83ce8db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dac28 RCX: 0000000000445979
RDX: 00000000200003c0 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac2c
R13: 00007ffed720031f R14: 00007fdb83ce99c0 R15: 20c49ba5e353f7cf
Code: 34 fe 89 d8 31 d2 f7 75 d4 83 f8 07 89 c3 41 89 c4 76 49 44 8d 60 f8 41 c1 ec 03 49 83 c4 01 49 c1 e4 06 4d 01 f4 e8 d4 ac 34 fe <4d> 89 3e 4d 89 7e 08 4d 89 7e 10 4d 89 7e 18 4d 89 7e 20 4d 89 

Crashes (241):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2019/12/03 08:18 linux-4.14.y fbc5fe7a54d0 ab342da3 .config log report syz C
ci2-linux-4-14 2020/01/02 06:26 linux-4.14.y 4c5bf01e16a7 25a0186e .config log report syz
ci2-linux-4-14 2019/12/21 13:27 linux-4.14.y e1f7d50ae3a3 bc586918 .config log report syz
ci2-linux-4-14 2020/09/24 12:30 linux-4.14.y cbfa1702aaf6 54289b08 .config log report info
ci2-linux-4-14 2020/07/29 05:38 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/29 01:07 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/28 16:28 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/28 13:30 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/28 06:57 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/27 18:31 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/27 07:48 linux-4.14.y 69b94dd6dcd1 cb93dc6a .config log report
ci2-linux-4-14 2020/07/26 22:45 linux-4.14.y 69b94dd6dcd1 51265195 .config log report
ci2-linux-4-14 2020/07/26 05:59 linux-4.14.y 69b94dd6dcd1 1f7cc1ca .config log report
ci2-linux-4-14 2020/07/25 22:46 linux-4.14.y 69b94dd6dcd1 1f7cc1ca .config log report
ci2-linux-4-14 2020/07/25 05:16 linux-4.14.y 69b94dd6dcd1 0a13649c .config log report
ci2-linux-4-14 2020/07/24 20:04 linux-4.14.y 69b94dd6dcd1 554af388 .config log report
ci2-linux-4-14 2020/07/24 10:17 linux-4.14.y 69b94dd6dcd1 70c104a1 .config log report
ci2-linux-4-14 2020/07/24 03:27 linux-4.14.y 69b94dd6dcd1 70c104a1 .config log report
ci2-linux-4-14 2020/07/20 20:14 linux-4.14.y b850307b279c 8caeeeb7 .config log report
ci2-linux-4-14 2020/07/19 21:43 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/19 14:31 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/19 04:34 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/18 22:34 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/18 20:02 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/18 12:53 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/17 18:54 linux-4.14.y b850307b279c 9c812472 .config log report
ci2-linux-4-14 2020/07/16 11:48 linux-4.14.y b850307b279c b090c643 .config log report
ci2-linux-4-14 2020/07/16 11:03 linux-4.14.y b850307b279c b090c643 .config log report
ci2-linux-4-14 2020/07/16 09:24 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/16 03:48 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/16 02:40 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/16 00:58 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 22:05 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 20:50 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 19:10 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 16:18 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 12:29 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 10:42 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 08:39 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/15 06:20 linux-4.14.y b850307b279c ada108d0 .config log report
ci2-linux-4-14 2020/07/14 21:42 linux-4.14.y b850307b279c 6f458026 .config log report
ci2-linux-4-14 2020/07/14 07:17 linux-4.14.y b850307b279c ce4c95b3 .config log report
ci2-linux-4-14 2020/07/13 03:59 linux-4.14.y b850307b279c 9ebcc5b1 .config log report
ci2-linux-4-14 2020/07/09 22:52 linux-4.14.y b850307b279c edf162e8 .config log report