Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.37' (ECDSA) to the list of known hosts. 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 syzkaller login: [ 29.729900] [ 29.729902] ============================================ [ 29.729903] WARNING: possible recursive locking detected [ 29.729907] 4.14.225-syzkaller #0 Not tainted [ 29.729908] -------------------------------------------- [ 29.729912] syz-executor522/7984 is trying to acquire lock: [ 29.729913] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 29.729927] [ 29.729927] but task is already holding lock: [ 29.729928] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 29.729935] [ 29.729935] other info that might help us debug this: [ 29.729936] Possible unsafe locking scenario: [ 29.729936] [ 29.729937] CPU0 [ 29.729938] ---- [ 29.729938] lock((fb_notifier_list).rwsem); [ 29.729941] lock((fb_notifier_list).rwsem); [ 29.729943] [ 29.729943] *** DEADLOCK *** [ 29.729943] [ 29.729944] May be due to missing lock nesting notation [ 29.729944] [ 29.729947] 3 locks held by syz-executor522/7984: [ 29.729948] #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x81a/0xa70 [ 29.729957] #1: (&fb_info->lock){+.+.}, at: [] do_fb_ioctl+0x824/0xa70 [ 29.729964] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 29.729971] [ 29.729971] stack backtrace: [ 29.730012] CPU: 1 PID: 7984 Comm: syz-executor522 Not tainted 4.14.225-syzkaller #0 [ 29.730014] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.730016] Call Trace: [ 29.730026] dump_stack+0x1b2/0x281 [ 29.730034] __lock_acquire.cold+0x180/0x97c [ 29.730041] ? trace_hardirqs_on+0x10/0x10 [ 29.730048] ? check_preemption_disabled+0x35/0x240 [ 29.730053] ? delay_tsc+0x8a/0xb0 [ 29.730057] ? vga16fb_update_fix+0x2fe/0x470 [ 29.730062] ? memcpy+0x35/0x50 [ 29.730065] lock_acquire+0x170/0x3f0 [ 29.730069] ? blocking_notifier_call_chain+0x63/0x90 [ 29.730075] down_read+0x36/0x80 [ 29.730079] ? blocking_notifier_call_chain+0x63/0x90 [ 29.730082] blocking_notifier_call_chain+0x63/0x90 [ 29.730086] fb_set_var+0xac5/0xc90 [ 29.730090] ? fb_set_suspend+0x110/0x110 [ 29.730096] ? vga16fb_imageblit+0x630/0x2140 [ 29.730100] ? fb_pad_aligned_buffer+0xbf/0x110 [ 29.730106] ? bit_cursor+0xfb8/0x1580 [ 29.730110] ? fb_videomode_to_var+0xf/0x610 [ 29.730114] fbcon_switch+0x3d9/0x19e0 [ 29.730119] ? fbcon_event_notify+0x1760/0x1760 [ 29.730127] redraw_screen+0x32c/0x790 [ 29.730131] ? get_color+0x1be/0x3a0 [ 29.730134] ? con_shutdown+0x90/0x90 [ 29.730137] ? bit_update_start+0x1f0/0x1f0 [ 29.730140] ? fbcon_cursor+0x480/0x640 [ 29.730143] fbcon_blank+0x986/0xd50 [ 29.730148] ? con2fb_release_oldinfo.constprop.0+0x5a0/0x5a0 [ 29.730151] ? __lock_acquire+0x5fc/0x3f20 [ 29.730156] ? trace_hardirqs_on+0x10/0x10 [ 29.730160] ? __lock_acquire+0x5fc/0x3f20 [ 29.730165] do_unblank_screen+0x1fd/0x4e0 [ 29.730169] fbcon_event_notify+0x1445/0x1760 [ 29.730173] notifier_call_chain+0x108/0x1a0 [ 29.730178] blocking_notifier_call_chain+0x79/0x90 [ 29.730182] fb_blank+0x14c/0x190 [ 29.730186] ? fb_set_logocmap+0x450/0x450 [ 29.730189] ? do_fb_ioctl+0x81a/0xa70 [ 29.730193] do_fb_ioctl+0x894/0xa70 [ 29.730197] ? register_framebuffer+0x8e0/0x8e0 [ 29.730200] ? __kernel_text_address+0x9/0x30 [ 29.730206] ? unwind_get_return_address+0x51/0x90 [ 29.730211] ? entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 29.730215] ? __save_stack_trace+0xa0/0x160 [ 29.730219] ? check_preemption_disabled+0x35/0x240 [ 29.730223] ? kasan_slab_free+0x12d/0x1a0 [ 29.730226] ? kasan_slab_free+0xc3/0x1a0 [ 29.730231] ? kmem_cache_free+0x7c/0x2b0 [ 29.730236] ? putname+0xcd/0x110 [ 29.730240] ? do_sys_open+0x203/0x410 [ 29.730245] ? do_syscall_64+0x1d5/0x640 [ 29.730248] ? entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 29.730252] ? path_lookupat+0x780/0x780 [ 29.730256] ? debug_check_no_obj_freed+0x2c0/0x680 [ 29.730260] ? lock_acquire+0x170/0x3f0 [ 29.730263] ? lock_downgrade+0x740/0x740 [ 29.730268] ? _raw_spin_unlock_irqrestore+0x66/0xe0 [ 29.730271] ? debug_check_no_obj_freed+0x2c0/0x680 [ 29.730275] fb_ioctl+0xdd/0x130 [ 29.730278] ? do_fb_ioctl+0xa70/0xa70 [ 29.730282] do_vfs_ioctl+0x75a/0xff0 [ 29.730287] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 29.730290] ? ioctl_preallocate+0x1a0/0x1a0 [ 29.730294] ? kmem_cache_free+0x23a/0x2b0 [ 29.730297] ? putname+0xcd/0x110 [ 29.730301] ? do_sys_open+0x208/0x410 [ 29.730304] ? filp_open+0x60/0x60 [ 29.730309] ? security_file_ioctl+0x83/0xb0 [ 29.730312] SyS_ioctl+0x7f/0xb0 [ 29.730315] ? do_vfs_ioctl+0xff0/0xff0 [ 29.730319] do_syscall_64+0x1d5/0x640 [ 29.730324] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 29.730328] RIP: 0033:0x440119 [ 29.730330] RSP: 002b:00007fff68029928 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 29.730334] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 0000000000440119 [ 29.730336] RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000006 [ 29.730338] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 [ 29.730340] R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000071b7 [ 29.730343] R13: 00007fff6802993c R14: 00007fff68029950 R15: 00007fff68029940 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 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 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