[ 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... Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.104' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program executing program syzkaller login: [ 27.854711] [ 27.854713] ============================================ [ 27.854714] WARNING: possible recursive locking detected [ 27.854718] 4.14.292-syzkaller #0 Not tainted [ 27.854719] -------------------------------------------- [ 27.854722] syz-executor297/7987 is trying to acquire lock: [ 27.854723] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 27.854737] [ 27.854737] but task is already holding lock: [ 27.854737] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 27.854744] [ 27.854744] other info that might help us debug this: [ 27.854745] Possible unsafe locking scenario: [ 27.854745] [ 27.854746] CPU0 [ 27.854747] ---- [ 27.854748] lock((fb_notifier_list).rwsem); [ 27.854750] lock((fb_notifier_list).rwsem); [ 27.854752] [ 27.854752] *** DEADLOCK *** [ 27.854752] [ 27.854753] May be due to missing lock nesting notation [ 27.854753] [ 27.854755] 3 locks held by syz-executor297/7987: [ 27.854756] #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x81a/0xa70 [ 27.854764] #1: (&fb_info->lock){+.+.}, at: [] do_fb_ioctl+0x824/0xa70 [ 27.854770] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 [ 27.854777] [ 27.854777] stack backtrace: [ 27.854781] CPU: 1 PID: 7987 Comm: syz-executor297 Not tainted 4.14.292-syzkaller #0 [ 27.854783] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 [ 27.854784] Call Trace: [ 27.854792] dump_stack+0x1b2/0x281 [ 27.854798] __lock_acquire.cold+0x180/0x97c [ 27.854804] ? retint_kernel+0x2d/0x2d [ 27.854809] ? trace_hardirqs_on+0x10/0x10 [ 27.854814] ? check_preemption_disabled+0x35/0x240 [ 27.854819] ? delay_tsc+0x8a/0xb0 [ 27.854824] ? vga16fb_update_fix+0x2fe/0x470 [ 27.854828] ? memcpy+0x35/0x50 [ 27.854832] lock_acquire+0x170/0x3f0 [ 27.854836] ? blocking_notifier_call_chain+0x63/0x90 [ 27.854840] down_read+0x36/0x80 [ 27.854845] ? blocking_notifier_call_chain+0x63/0x90 [ 27.854848] blocking_notifier_call_chain+0x63/0x90 [ 27.854854] fb_set_var+0xbc8/0xdc0 [ 27.854859] ? fb_set_suspend+0x110/0x110 [ 27.854864] ? vga16fb_imageblit+0x630/0x2140 [ 27.854868] ? fb_pad_aligned_buffer+0xbf/0x110 [ 27.854874] ? bit_cursor+0xfb8/0x1580 [ 27.854878] ? fb_videomode_to_var+0xf/0x610 [ 27.854881] fbcon_switch+0x3d9/0x19e0 [ 27.854886] ? fbcon_event_notify+0x1760/0x1760 [ 27.854892] redraw_screen+0x32c/0x790 [ 27.854896] ? get_color+0x1be/0x3a0 [ 27.854899] ? con_shutdown+0x90/0x90 [ 27.854902] ? bit_update_start+0x1f0/0x1f0 [ 27.854905] ? fbcon_cursor+0x48e/0x650 [ 27.854909] fbcon_blank+0x986/0xd50 [ 27.854913] ? con2fb_release_oldinfo.constprop.0+0x5a0/0x5a0 [ 27.854916] ? __lock_acquire+0x5fc/0x3f20 [ 27.854921] ? trace_hardirqs_on+0x10/0x10 [ 27.854925] ? __lock_acquire+0x5fc/0x3f20 [ 27.854929] do_unblank_screen+0x1fd/0x4e0 [ 27.854933] fbcon_event_notify+0x1445/0x1760 [ 27.854937] notifier_call_chain+0x108/0x1a0 [ 27.854942] blocking_notifier_call_chain+0x79/0x90 [ 27.854946] fb_blank+0x14c/0x190 [ 27.854949] ? fb_set_logocmap+0x450/0x450 [ 27.854952] ? do_fb_ioctl+0x81a/0xa70 [ 27.854956] do_fb_ioctl+0x894/0xa70 [ 27.854959] ? register_framebuffer+0x8e0/0x8e0 [ 27.854963] ? lock_downgrade+0x740/0x740 [ 27.854967] ? __lru_cache_add+0x178/0x250 [ 27.854972] ? page_remove_rmap.part.0+0xe/0x190 [ 27.854976] ? do_raw_spin_unlock+0x164/0x220 [ 27.854979] ? _raw_spin_unlock+0x29/0x40 [ 27.854982] ? wp_page_copy+0xf91/0x25c0 [ 27.854986] ? tlb_flush_mmu_free+0x1a0/0x1a0 [ 27.854989] ? __lock_acquire+0x5fc/0x3f20 [ 27.854993] ? do_wp_page+0x24d/0x1db0 [ 27.854996] ? __handle_mm_fault+0x129c/0x4620 [ 27.854999] ? finish_mkwrite_fault+0x5e0/0x5e0 [ 27.855003] ? __handle_mm_fault+0x80f/0x4620 [ 27.855006] fb_ioctl+0xdd/0x130 [ 27.855009] ? do_fb_ioctl+0xa70/0xa70 [ 27.855013] do_vfs_ioctl+0x75a/0xff0 [ 27.855016] ? ioctl_preallocate+0x1a0/0x1a0 [ 27.855020] ? lock_downgrade+0x740/0x740 [ 27.855026] ? security_file_ioctl+0x83/0xb0 [ 27.855030] SyS_ioctl+0x7f/0xb0 [ 27.855033] ? do_vfs_ioctl+0xff0/0xff0 [ 27.855037] do_syscall_64+0x1d5/0x640 [ 27.855041] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 27.855045] RIP: 0033:0x7fb332166279 [ 27.855047] RSP: 002b:00007fffe071ff58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 27.855051] RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007fb332166279 [ 27.855053] RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000003 [ 27.855055] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 [ 27.855057] R10: 00007fffe071f9d0 R11: 0000000000000246 R12: 00007fb332129a50 [ 27.855059] R13: 0000000000000000 R14: 00007fffe071ff80 R15: 00007fffe071ff70 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 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