[ OK ] Started Getty on tty2. [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ 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. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.124' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 28.831089] [ 28.831091] ============================================ [ 28.831092] WARNING: possible recursive locking detected [ 28.831097] 4.14.218-syzkaller #0 Not tainted [ 28.831098] -------------------------------------------- [ 28.831101] syz-executor384/7967 is trying to acquire lock: [ 28.831102] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 28.831117] [ 28.831117] but task is already holding lock: [ 28.831118] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 28.831125] [ 28.831125] other info that might help us debug this: [ 28.831126] Possible unsafe locking scenario: [ 28.831126] [ 28.831127] CPU0 [ 28.831128] ---- [ 28.831129] lock((fb_notifier_list).rwsem); [ 28.831131] lock((fb_notifier_list).rwsem); [ 28.831134] [ 28.831134] *** DEADLOCK *** [ 28.831134] [ 28.831135] May be due to missing lock nesting notation [ 28.831135] [ 28.831137] 3 locks held by syz-executor384/7967: [ 28.831138] #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x81a/0xa70 [ 28.831147] #1: (&fb_info->lock){+.+.}, at: [] do_fb_ioctl+0x824/0xa70 [ 28.831153] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 28.831160] [ 28.831160] stack backtrace: [ 28.831164] CPU: 1 PID: 7967 Comm: syz-executor384 Not tainted 4.14.218-syzkaller #0 [ 28.831166] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.831168] Call Trace: [ 28.831176] dump_stack+0x1b2/0x281 [ 28.831182] __lock_acquire.cold+0x180/0x97c [ 28.831190] ? trace_hardirqs_on+0x10/0x10 [ 28.831197] ? check_preemption_disabled+0x35/0x240 [ 28.831202] ? delay_tsc+0x8a/0xb0 [ 28.831207] ? vga16fb_update_fix+0x376/0x470 [ 28.831212] ? memcpy+0x35/0x50 [ 28.831215] lock_acquire+0x170/0x3f0 [ 28.831219] ? blocking_notifier_call_chain+0x63/0x90 [ 28.831225] down_read+0x36/0x80 [ 28.831229] ? blocking_notifier_call_chain+0x63/0x90 [ 28.831232] blocking_notifier_call_chain+0x63/0x90 [ 28.831236] fb_set_var+0xac5/0xc90 [ 28.831240] ? fb_set_suspend+0x110/0x110 [ 28.831250] ? kasan_slab_free+0xc3/0x1a0 [ 28.831255] ? kfree+0xc9/0x250 [ 28.831260] ? vga16fb_imageblit+0x630/0x2140 [ 28.831264] ? fb_pad_aligned_buffer+0xbf/0x110 [ 28.831270] ? bit_cursor+0xfb8/0x1580 [ 28.831274] ? fb_videomode_to_var+0xf/0x610 [ 28.831277] fbcon_switch+0x3d9/0x19e0 [ 28.831282] ? fbcon_event_notify+0x1760/0x1760 [ 28.831291] redraw_screen+0x32c/0x790 [ 28.831295] ? get_color+0x1be/0x3a0 [ 28.831299] ? con_shutdown+0x90/0x90 [ 28.831302] ? bit_update_start+0x1f0/0x1f0 [ 28.831304] ? fbcon_cursor+0x480/0x640 [ 28.831308] fbcon_blank+0x986/0xd50 [ 28.831312] ? con2fb_release_oldinfo.constprop.0+0x5a0/0x5a0 [ 28.831316] ? __lock_acquire+0x5fc/0x3f20 [ 28.831320] ? __lock_acquire+0x5fc/0x3f20 [ 28.831324] ? trace_hardirqs_on+0x10/0x10 [ 28.831328] ? __lock_acquire+0x5fc/0x3f20 [ 28.831333] do_unblank_screen+0x1fd/0x4e0 [ 28.831337] fbcon_event_notify+0x1445/0x1760 [ 28.831341] notifier_call_chain+0x108/0x1a0 [ 28.831346] blocking_notifier_call_chain+0x79/0x90 [ 28.831350] fb_blank+0x14c/0x190 [ 28.831353] ? fb_set_logocmap+0x450/0x450 [ 28.831356] ? do_fb_ioctl+0x81a/0xa70 [ 28.831360] do_fb_ioctl+0x894/0xa70 [ 28.831364] ? register_framebuffer+0x8e0/0x8e0 [ 28.831368] ? __kernel_text_address+0x9/0x30 [ 28.831373] ? unwind_get_return_address+0x51/0x90 [ 28.831377] ? entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 28.831382] ? __save_stack_trace+0xa0/0x160 [ 28.831386] ? check_preemption_disabled+0x35/0x240 [ 28.831390] ? kasan_slab_free+0x12d/0x1a0 [ 28.831393] ? kasan_slab_free+0xc3/0x1a0 [ 28.831396] ? kmem_cache_free+0x7c/0x2b0 [ 28.831401] ? putname+0xcd/0x110 [ 28.831405] ? do_sys_open+0x203/0x410 [ 28.831409] ? do_syscall_64+0x1d5/0x640 [ 28.831413] ? entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 28.831417] ? path_lookupat+0x780/0x780 [ 28.831420] ? debug_check_no_obj_freed+0x2c0/0x680 [ 28.831424] ? lock_acquire+0x170/0x3f0 [ 28.831428] ? lock_downgrade+0x740/0x740 [ 28.831433] ? _raw_spin_unlock_irqrestore+0x66/0xe0 [ 28.831436] ? debug_check_no_obj_freed+0x2c0/0x680 [ 28.831440] fb_ioctl+0xdd/0x130 [ 28.831443] ? do_fb_ioctl+0xa70/0xa70 [ 28.831447] do_vfs_ioctl+0x75a/0xff0 [ 28.831451] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 28.831454] ? ioctl_preallocate+0x1a0/0x1a0 [ 28.831458] ? kmem_cache_free+0x23a/0x2b0 [ 28.831461] ? putname+0xcd/0x110 [ 28.831465] ? do_sys_open+0x208/0x410 [ 28.831468] ? filp_open+0x60/0x60 [ 28.831473] ? security_file_ioctl+0x83/0xb0 [ 28.831476] SyS_ioctl+0x7f/0xb0 [ 28.831479] ? do_vfs_ioctl+0xff0/0xff0 [ 28.831482] do_syscall_64+0x1d5/0x640 [ 28.831487] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 28.831491] RIP: 0033:0x440029 [ 28.831493] RSP: 002b:00007ffff26aa318 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 28.831497] RAX: ffffffffffffffda RBX: 000000000000700a RCX: 0000000000440029 [ 28.831499] RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000004 [ 28.831501] RBP: 0000000000000000 R08: 00007ffff26aa4b8 R09: 00007ffff26aa4b8 [ 28.831503] R10: 00007ffff26aa4b8 R11: 0000000000000246 R12: 00007ffff26aa32c [ 28.831505] R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488 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 executing program executing program executing program executing program