syzbot


INFO: task hung in con_write

Status: auto-closed as invalid on 2020/03/14 17:26
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 975d, last: 975d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in con_write (2) 3 762d 810d 0/23 auto-closed as invalid on 2020/10/13 06:51
linux-4.19 INFO: task hung in con_write 2 790d 857d 0/1 auto-closed as invalid on 2020/10/15 09:20
linux-4.14 INFO: task hung in con_write 1 820d 820d 0/1 auto-closed as invalid on 2020/09/14 21:41

Sample crash report:
INFO: task syz-executor.4:11126 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D27480 11126   9098 0x20024004
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x176/0x2c0 kernel/locking/semaphore.c:237
 down+0x64/0x90 kernel/locking/semaphore.c:61
 console_lock+0x29/0x80 kernel/printk/printk.c:2289
 con_flush_chars drivers/tty/vt/vt.c:3212 [inline]
 con_flush_chars drivers/tty/vt/vt.c:3204 [inline]
 con_write+0x83/0xd0 drivers/tty/vt/vt.c:3136
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x40e/0x1080 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:962 [inline]
 tty_write+0x496/0x7f0 drivers/tty/tty_io.c:1046
 __vfs_write+0x8a/0x110 fs/read_write.c:494
 vfs_write+0x268/0x5d0 fs/read_write.c:558
 ksys_write+0x14f/0x290 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __ia32_sys_write+0x71/0xb0 fs/read_write.c:620
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f80a39
Code: Bad RIP value.
RSP: 002b:00000000f5d7c0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000020000880
RDX: 00000000000002c1 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor.0:11143 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28144 11143   9087 0x20020004
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x176/0x2c0 kernel/locking/semaphore.c:237
 down+0x64/0x90 kernel/locking/semaphore.c:61
 console_lock+0x29/0x80 kernel/printk/printk.c:2289
 vcs_open+0x67/0xd0 drivers/tty/vt/vc_screen.c:688
 chrdev_open+0x245/0x6b0 fs/char_dev.c:414
 do_dentry_open+0x4e6/0x1380 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3420 [inline]
 path_openat+0x10df/0x4500 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3fe/0x5d0 fs/open.c:1097
 __do_compat_sys_openat fs/open.c:1143 [inline]
 __se_compat_sys_openat fs/open.c:1141 [inline]
 __ia32_compat_sys_openat+0x98/0xf0 fs/open.c:1141
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f75a39
Code: Bad RIP value.
RSP: 002b:00000000f5d500cc EFLAGS: 00000296 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 0000000020000080
RDX: 0000000000002900 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor.0:11148 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28520 11148   9087 0x20020004
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871
 __down_common kernel/locking/semaphore.c:220 [inline]
 __down+0x176/0x2c0 kernel/locking/semaphore.c:237
 down+0x64/0x90 kernel/locking/semaphore.c:61
 console_lock+0x29/0x80 kernel/printk/printk.c:2289
 vcs_open+0x67/0xd0 drivers/tty/vt/vc_screen.c:688
 chrdev_open+0x245/0x6b0 fs/char_dev.c:414
 do_dentry_open+0x4e6/0x1380 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3420 [inline]
 path_openat+0x10df/0x4500 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3fe/0x5d0 fs/open.c:1097
 __do_compat_sys_openat fs/open.c:1143 [inline]
 __se_compat_sys_openat fs/open.c:1141 [inline]
 __ia32_compat_sys_openat+0x98/0xf0 fs/open.c:1141
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f75a39
Code: Bad RIP value.
RSP: 002b:00000000f5d2f0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 0000000020000080
RDX: 0000000000002900 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
INFO: task syz-executor.0:11150 blocked for more than 143 seconds.
      Not tainted 5.5.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D28520 11150   9087 0x20024004
Call Trace:
 context_switch kernel/sched/core.c:3385 [inline]
 __schedule+0x934/0x1f90 kernel/sched/core.c:4081
 schedule+0xdc/0x2b0 kernel/sched/core.c:4155
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214
 __mutex_lock_common kernel/locking/mutex.c:1036 [inline]
 __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1106
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1121
 lock_fb_info include/linux/fb.h:637 [inline]
 fb_open+0xd7/0x450 drivers/video/fbdev/core/fbmem.c:1406
 chrdev_open+0x245/0x6b0 fs/char_dev.c:414
 do_dentry_open+0x4e6/0x1380 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3420 [inline]
 path_openat+0x10df/0x4500 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3fe/0x5d0 fs/open.c:1097
 __do_compat_sys_openat fs/open.c:1143 [inline]
 __se_compat_sys_openat fs/open.c:1141 [inline]
 __ia32_compat_sys_openat+0x98/0xf0 fs/open.c:1141
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f75a39
Code: Bad RIP value.
RSP: 002b:00000000f5d0e0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 0000000020000140
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1112:
 #0: ffffffff899a56c0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334
1 lock held by rsyslogd/8959:
 #0: ffff888098700360 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801
2 locks held by getty/9049:
 #0: ffff88809828c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017ab2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9050:
 #0: ffff88809819a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9051:
 #0: ffff8880a0be9090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017db2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9052:
 #0: ffff8880a4a57090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9053:
 #0: ffff888094e24090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9054:
 #0: ffff8880a8098090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
2 locks held by getty/9055:
 #0: ffff8880a66ae090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffffc9000171b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156
4 locks held by syz-executor.4/11126:
 #0: ffff88809828c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340
 #1: ffff88809828c118 (&tty->atomic_write_lock){+.+.}, at: tty_write_lock+0x55/0x90 drivers/tty/tty_io.c:891
 #2: ffff88809828c2a0 (&tty->termios_rwsem){++++}, at: n_tty_write+0x1b5/0x1080 drivers/tty/n_tty.c:2316
 #3: ffffc900017ab360 (&ldata->output_lock){+.+.}, at: process_output_block drivers/tty/n_tty.c:550 [inline]
 #3: ffffc900017ab360 (&ldata->output_lock){+.+.}, at: n_tty_write+0x548/0x1080 drivers/tty/n_tty.c:2333
2 locks held by syz-executor.0/11140:
1 lock held by syz-executor.0/11150:
 #0: ffff888218ca5070 (&fb_info->lock){+.+.}, at: lock_fb_info include/linux/fb.h:637 [inline]
 #0: ffff888218ca5070 (&fb_info->lock){+.+.}, at: fb_open+0xd7/0x450 drivers/video/fbdev/core/fbmem.c:1406

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

NMI backtrace for cpu 0
CPU: 0 PID: 1112 Comm: khungtaskd Not tainted 5.5.0-rc1-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+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:205 [inline]
 watchdog+0xb11/0x10c0 kernel/hung_task.c:289
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 11140 Comm: syz-executor.0 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:155 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x20/0x50 kernel/kcov.c:187
Code: 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 65 48 8b 04 25 c0 1e 02 00 65 8b 15 e4 f2 8c 7e 81 e2 00 01 1f 00 48 8b 75 08 75 2b <8b> 90 80 13 00 00 83 fa 02 75 20 48 8b 88 88 13 00 00 8b 80 84 13
RSP: 0018:ffffc90007657448 EFLAGS: 00000246
RAX: ffff8880a00361c0 RBX: ffff8880000a006d RCX: ffffffff83b8d0e8
RDX: 0000000000000000 RSI: ffffffff83b8d0be RDI: 0000000000000005
RBP: ffffc90007657448 R08: ffff8880a00361c0 R09: ffffed104319e66c
R10: ffffed104319e66b R11: ffff888218cf335f R12: 0000000000000003
R13: fffff52000ecaea2 R14: 0000000000000033 R15: ffffc90007657500
FS:  0000000000000000(0000) GS:ffff8880ae900000(0063) knlGS:00000000f5d71b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000000998a5000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 vga_8planes_fillrect drivers/video/fbdev/vga16fb.c:855 [inline]
 vga16fb_fillrect+0xece/0x19b0 drivers/video/fbdev/vga16fb.c:947
 bit_clear_margins+0x30b/0x530 drivers/video/fbdev/core/bitblit.c:232
 fbcon_clear_margins+0x1e9/0x250 drivers/video/fbdev/core/fbcon.c:1372
 fbcon_switch+0xd7f/0x17f0 drivers/video/fbdev/core/fbcon.c:2354
 redraw_screen+0x2b6/0x7d0 drivers/tty/vt/vt.c:997
 fbcon_modechanged+0x5c3/0x790 drivers/video/fbdev/core/fbcon.c:2991
 fbcon_update_vcs+0x42/0x50 drivers/video/fbdev/core/fbcon.c:3038
 fb_set_var+0xb32/0xdd0 drivers/video/fbdev/core/fbmem.c:1051
 do_fb_ioctl+0x390/0x7d0 drivers/video/fbdev/core/fbmem.c:1104
 fb_compat_ioctl+0x305/0xc50 drivers/video/fbdev/core/fbmem.c:1310
 __do_compat_sys_ioctl fs/compat_ioctl.c:214 [inline]
 __se_compat_sys_ioctl fs/compat_ioctl.c:142 [inline]
 __ia32_compat_sys_ioctl+0x233/0x610 fs/compat_ioctl.c:142
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f75a39
Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5d710cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000004601
RDX: 00000000200002c0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-386 2019/12/15 17:18 upstream 07c4b9e9f71a eef6e580 .config log report