syzbot


INFO: task hung in con_font_op

Status: auto-closed as invalid on 2020/04/17 20:41
Reported-by: syzbot+75cb72f274763394c73a@syzkaller.appspotmail.com
First crash: 920d, last: 920d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in con_font_op 3 785d 914d 0/1 auto-closed as invalid on 2020/08/30 22:32
upstream INFO: task hung in con_font_op 2 759d 772d 0/22 auto-closed as invalid on 2020/08/26 18:47

Sample crash report:
kobject: 'kvm' (ffff888219463290): fill_kobj_path: path = '/devices/virtual/misc/kvm'
kobject: 'kvm' (ffff888219463290): kobject_uevent_env
kobject: 'kvm' (ffff888219463290): fill_kobj_path: path = '/devices/virtual/misc/kvm'
kobject: 'kvm' (ffff888219463290): kobject_uevent_env
kobject: 'kvm' (ffff888219463290): fill_kobj_path: path = '/devices/virtual/misc/kvm'
INFO: task syz-executor.3:12331 blocked for more than 140 seconds.
      Not tainted 4.14.159-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D28024 12331  12303 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
 con_font_get drivers/tty/vt/vt.c:4074 [inline]
 con_font_op+0x130/0x1060 drivers/tty/vt/vt.c:4229
 vt_ioctl+0xb80/0x2170 drivers/tty/vt/vt_ioctl.c:927
 tty_ioctl+0x841/0x1320 drivers/tty/tty_io.c:2661
 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: 0033:0x45a919
RSP: 002b:00007ff54341dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000200 RSI: 0000000000004b60 RDI: 0000000000000008
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff54341e6d4
R13: 00000000004c3552 R14: 00000000004d89d0 R15: 00000000ffffffff
INFO: task syz-executor.3:12335 blocked for more than 140 seconds.
      Not tainted 4.14.159-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3  D29328 12335  12303 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
 con_font_get drivers/tty/vt/vt.c:4074 [inline]
 con_font_op+0x130/0x1060 drivers/tty/vt/vt.c:4229
 vt_ioctl+0xb80/0x2170 drivers/tty/vt/vt_ioctl.c:927
 tty_ioctl+0x841/0x1320 drivers/tty/tty_io.c:2661
 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: 0033:0x45a919
RSP: 002b:00007ff5433dac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000200 RSI: 0000000000004b60 RDI: 0000000000000006
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff5433db6d4
R13: 00000000004c3552 R14: 00000000004d89d0 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1044:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff8148c8d8>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
1 lock held by rsyslogd/6937:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff81966a5b>] __fdget_pos+0xab/0xd0 fs/file.c:769
2 locks held by getty/7060:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7061:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7062:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7063:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7064:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7065:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7066:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 1
CPU: 1 PID: 1044 Comm: khungtaskd Not tainted 4.14.159-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: 12317 Comm: syz-executor.1 Not tainted 4.14.159-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888059e44240 task.stack: ffff8880801e8000
RIP: 0010:__sanitizer_cov_trace_pc+0x51/0x60 kernel/kcov.c:93
RSP: 0018:ffff8880801ef260 EFLAGS: 00000246
RAX: 0000000000040000 RBX: 0000000000000240 RCX: ffffc90005a84000
RDX: 0000000000040000 RSI: ffffffff8328b10f RDI: ffff8880a5852cc0
RBP: ffff8880801ef260 R08: 0000000000000240 R09: 0000000000000040
R10: ffffed1014bf5783 R11: ffff8880a5fabc1f R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880000a0000 R15: 0000000000000000
FS:  00007f4f7f109700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c422d055f0 CR3: 000000005c6dd000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bitfill_aligned drivers/video/fbdev/core/cfbfillrect.c:43 [inline]
 bitfill_aligned+0x2f/0x190 drivers/video/fbdev/core/cfbfillrect.c:35
 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: 0033:0x45a919
RSP: 002b:00007f4f7f108c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000020000000 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4f7f1096d4
R13: 00000000004c310d R14: 00000000004d8478 R15: 00000000ffffffff
Code: 74 01 c3 55 48 89 e5 48 8b 75 08 48 8b 88 58 13 00 00 8b 80 54 13 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 <5d> c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2019/12/19 20:40 linux-4.14.y bfb9e5c03076 36650b4b .config log report