general protection fault in fbcon_event_notify

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: fb683b5e Linux 4.19.88
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1060690ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=aa0c39a6a0078b1c
dashboard link: https://syzkaller.appspot.com/bug?extid=75a72895ac3b23f53ccc
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+75a728...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 14866 Comm: syz-executor.1 Not tainted 4.19.88-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:fbcon_fb_blanked drivers/video/fbdev/core/fbcon.c:3248 [inline]
RIP: 0010:fbcon_event_notify+0xa88/0x1dba
drivers/video/fbdev/core/fbcon.c:3374
Code: 0f 85 2b 13 00 00 48 8d 04 db 4c 8b 3c c5 a0 f9 6c 8b 48 b8 00 00 00
00 00 fc ff df 49 8d bf 7c 03 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48
89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 fb 12 00 00
RSP: 0018:ffff88804d597840 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 000000000000003e RCX: ffffc900080a7000
RDX: 000000000000006f RSI: ffffffff838225bd RDI: 000000000000037c
RBP: ffff88804d5978a0 R08: ffff88807cf4e500 R09: 0000000000000002
R10: ffff88807cf4edd0 R11: ffffffff8a769560 R12: ffff888219711700
R13: ffff88804d5979b8 R14: ffff888219a44540 R15: 0000000000000000
FS: 00007f1b7b9c1700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000738000 CR3: 000000004d75d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
notifier_call_chain+0xc2/0x230 kernel/notifier.c:93
__blocking_notifier_call_chain kernel/notifier.c:317 [inline]
__blocking_notifier_call_chain kernel/notifier.c:304 [inline]
blocking_notifier_call_chain kernel/notifier.c:328 [inline]
blocking_notifier_call_chain+0x94/0xb0 kernel/notifier.c:325
fb_notifier_call_chain+0x25/0x30 drivers/video/fbdev/core/fb_notify.c:45
fb_blank+0x1b5/0x200 drivers/video/fbdev/core/fbmem.c:1070
do_fb_ioctl+0x1d9/0xab0 drivers/video/fbdev/core/fbmem.c:1206
fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1230
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:501 [inline]
do_vfs_ioctl+0xd5f/0x1380 fs/ioctl.c:688
ksys_ioctl+0xab/0xd0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:710
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a6f9
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1b7b9c0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6f9
RDX: 0000000000000003 RSI: 0000000000004611 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1b7b9c16d4
R13: 00000000004c2e49 R14: 00000000004d8118 R15: 00000000ffffffff
Modules linked in:
---[ end trace cc0aa3cba1ef73c4 ]---
RIP: 0010:fbcon_fb_blanked drivers/video/fbdev/core/fbcon.c:3248 [inline]
RIP: 0010:fbcon_event_notify+0xa88/0x1dba
drivers/video/fbdev/core/fbcon.c:3374
Code: 0f 85 2b 13 00 00 48 8d 04 db 4c 8b 3c c5 a0 f9 6c 8b 48 b8 00 00 00
00 00 fc ff df 49 8d bf 7c 03 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 48
89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 fb 12 00 00
RSP: 0018:ffff88804d597840 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 000000000000003e RCX: ffffc900080a7000
RDX: 000000000000006f RSI: ffffffff838225bd RDI: 000000000000037c
RBP: ffff88804d5978a0 R08: ffff88807cf4e500 R09: 0000000000000002
R10: ffff88807cf4edd0 R11: ffffffff8a769560 R12: ffff888219711700
R13: ffff88804d5979b8 R14: ffff888219a44540 R15: 0000000000000000
FS: 00007f1b7b9c1700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000738000 CR3: 000000004d75d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.