[ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.237' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 35.817839] [ 35.817841] ============================================ [ 35.817842] WARNING: possible recursive locking detected [ 35.817847] 4.14.176-syzkaller #0 Not tainted [ 35.817848] -------------------------------------------- [ 35.817851] syz-executor013/6330 is trying to acquire lock: [ 35.817852] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 35.817865] [ 35.817865] but task is already holding lock: [ 35.817866] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 35.817873] [ 35.817873] other info that might help us debug this: [ 35.817874] Possible unsafe locking scenario: [ 35.817874] [ 35.817875] CPU0 [ 35.817876] ---- [ 35.817876] lock((fb_notifier_list).rwsem); [ 35.817879] lock((fb_notifier_list).rwsem); [ 35.817881] [ 35.817881] *** DEADLOCK *** [ 35.817881] [ 35.817882] May be due to missing lock nesting notation [ 35.817882] [ 35.817885] 3 locks held by syz-executor013/6330: [ 35.817885] #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x143/0x940 [ 35.817894] #1: (&fb_info->lock){+.+.}, at: [] lock_fb_info+0x1a/0x70 [ 35.817900] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 35.817911] [ 35.817911] stack backtrace: [ 35.817915] CPU: 1 PID: 6330 Comm: syz-executor013 Not tainted 4.14.176-syzkaller #0 [ 35.817917] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.817919] Call Trace: [ 35.817930] dump_stack+0x13e/0x194 [ 35.817938] __lock_acquire.cold+0x2bf/0x8dc [ 35.817943] ? retint_kernel+0x2d/0x2d [ 35.817949] ? trace_hardirqs_on+0x10/0x10 [ 35.817953] ? save_trace+0x290/0x290 [ 35.817957] ? delay_tsc+0x8a/0xb0 [ 35.817961] lock_acquire+0x170/0x3f0 [ 35.817965] ? blocking_notifier_call_chain+0x63/0x90 [ 35.817969] down_read+0x37/0xa0 [ 35.817973] ? blocking_notifier_call_chain+0x63/0x90 [ 35.817976] blocking_notifier_call_chain+0x63/0x90 [ 35.817980] fb_set_var+0xaad/0xc70 [ 35.817984] ? fb_set_suspend+0x110/0x110 [ 35.817989] ? save_stack+0x89/0xa0 [ 35.817992] ? save_stack+0x32/0xa0 [ 35.817995] ? kasan_slab_free+0x75/0xc0 [ 35.817998] ? kfree+0xcb/0x260 [ 35.818003] ? bit_cursor+0x99a/0x1700 [ 35.818006] ? fbcon_cursor+0x4be/0x690 [ 35.818010] ? fbcon_blank+0x940/0xd60 [ 35.818015] ? do_unblank_screen+0x1fd/0x4f0 [ 35.818018] ? fbcon_event_notify+0x1433/0x1746 [ 35.818022] ? notifier_call_chain+0x107/0x1a0 [ 35.818025] ? blocking_notifier_call_chain+0x79/0x90 [ 35.818027] ? fb_blank+0x14c/0x190 [ 35.818031] ? vga16fb_imageblit+0xba0/0x2160 [ 35.818039] ? bit_cursor+0xacc/0x1700 [ 35.818043] ? fb_videomode_to_var+0xf/0x610 [ 35.818047] fbcon_switch+0x4b9/0x1780 [ 35.818052] ? fbcon_set_def_font+0x370/0x370 [ 35.818057] ? fbcon_cursor+0x4be/0x690 [ 35.818060] ? bit_clear+0x460/0x460 [ 35.818064] ? fbcon_set_origin+0x1c/0x40 [ 35.818067] ? fbcon_scrolldelta+0x10c0/0x10c0 [ 35.818071] redraw_screen+0x331/0x770 [ 35.818075] ? get_color+0x1b8/0x3a0 [ 35.818079] ? con_flush_chars+0x80/0x80 [ 35.818082] ? fbcon_cursor+0x4be/0x690 [ 35.818085] ? bit_clear+0x460/0x460 [ 35.818089] fbcon_blank+0x9b3/0xd60 [ 35.818094] ? fbcon_cursor+0x690/0x690 [ 35.818097] ? lock_acquire+0x170/0x3f0 [ 35.818100] ? fb_open+0xb7/0x400 [ 35.818104] ? save_trace+0x290/0x290 [ 35.818108] ? __lock_is_held+0xad/0x140 [ 35.818113] do_unblank_screen+0x1fd/0x4f0 [ 35.818118] fbcon_event_notify+0x1433/0x1746 [ 35.818122] ? lock_acquire+0x170/0x3f0 [ 35.818125] notifier_call_chain+0x107/0x1a0 [ 35.818130] blocking_notifier_call_chain+0x79/0x90 [ 35.818134] fb_blank+0x14c/0x190 [ 35.818137] ? fb_seq_stop+0x20/0x20 [ 35.818140] ? do_fb_ioctl+0x143/0x940 [ 35.818143] ? lock_fb_info+0x1a/0x70 [ 35.818146] do_fb_ioctl+0x196/0x940 [ 35.818150] ? lock_downgrade+0x6e0/0x6e0 [ 35.818153] ? fb_read+0x520/0x520 [ 35.818157] ? avc_has_extended_perms+0x802/0xd40 [ 35.818161] ? avc_ss_reset+0x100/0x100 [ 35.818165] ? save_stack+0x32/0xa0 [ 35.818168] ? kasan_slab_free+0x75/0xc0 [ 35.818170] ? kmem_cache_free+0x7c/0x2b0 [ 35.818174] ? putname+0xcd/0x110 [ 35.818178] ? do_sys_open+0x1f9/0x3f0 [ 35.818184] ? do_syscall_64+0x1d5/0x640 [ 35.818188] ? entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 35.818192] ? find_held_lock+0x2d/0x110 [ 35.818197] ? debug_check_no_obj_freed+0x28e/0x6e4 [ 35.818201] ? lock_acquire+0x170/0x3f0 [ 35.818204] ? lock_downgrade+0x6e0/0x6e0 [ 35.818209] fb_ioctl+0xdd/0x130 [ 35.818212] ? do_fb_ioctl+0x940/0x940 [ 35.818216] do_vfs_ioctl+0x75a/0xfe0 [ 35.818220] ? selinux_file_mprotect+0x5c0/0x5c0 [ 35.818224] ? ioctl_preallocate+0x1a0/0x1a0 [ 35.818229] ? rcu_read_lock_sched_held+0x10a/0x130 [ 35.818232] ? kmem_cache_free+0x23a/0x2b0 [ 35.818236] ? putname+0xcd/0x110 [ 35.818242] ? security_file_ioctl+0x76/0xb0 [ 35.818245] ? security_file_ioctl+0x83/0xb0 [ 35.818249] SyS_ioctl+0x7f/0xb0 [ 35.818252] ? do_vfs_ioctl+0xfe0/0xfe0 [ 35.818256] do_syscall_64+0x1d5/0x640 [ 35.818261] entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ 35.818265] RIP: 0033:0x4413c9 [ 35.818267] RSP: 002b:00007ffc5a2a0d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 35.818271] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004413c9 [ 35.818273] RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000004 executing program [ 35.818276] RBP: 0000000000008ac3 R08: 00000000004002c8 R09: 00000000004002c8 [ 35.818278] R10: 00000000004002c8 R11: 0000000000000246 R12: 00000000004021f0 [ 35.818280] R13: 0000000000402280 R14: 0000000000000000 R15: 0000000000000000 executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program