BUG: unable to handle kernel paging request in vga16fb_fillrect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: a844dc4c Linux 4.14.158
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16e71db6e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c02bef505ffc02ff
dashboard link: https://syzkaller.appspot.com/bug?extid=c3842fec80d859748648
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+c3842f...@syzkaller.appspotmail.com

kobject: 'loop4' (ffff8880a416a5a0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff888208d1c5e0): kobject_uevent_env
kobject: 'loop0' (ffff888208d1c5e0): fill_kobj_path: path
= '/devices/virtual/block/loop0'
audit: type=1800 audit(1576613952.621:2220): pid=1016 uid=0 auid=4294967295
ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
op="collect_data" cause="failed(directio)" comm="syz-executor.5"
name=CE8F2AF7 dev="sda1" ino=18381 res=0
BUG: unable to handle kernel paging request at ffff888000145000
IP: writeb arch/x86/include/asm/io.h:65 [inline]
IP: vga16fb_fillrect+0x940/0x1880 drivers/video/fbdev/vga16fb.c:923
PGD a56d067 P4D a56d067 PUD a56e067 PMD a56f067 PTE 8000000000145161
Oops: 0003 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 1007 Comm: syz-executor.1 Not tainted 4.14.158-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880541465c0 task.stack: ffff8881e9db0000
RIP: 0010:writeb arch/x86/include/asm/io.h:65 [inline]
RIP: 0010:vga16fb_fillrect+0x940/0x1880 drivers/video/fbdev/vga16fb.c:923
RSP: 0018:ffff8881e9db7330 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff8880200a0000 RCX: ffffc9000ce54000
RDX: 0000000000040000 RSI: ffffffff832c7d10 RDI: ffff8881e9db73f0
RBP: ffff8881e9db7398 R08: 00000000fffffe20 R09: ffffed1014b88e44
R10: ffffed1014b88e43 R11: ffff8880a5c4721f R12: 000000001fffffb0
R13: 0000000000000000 R14: 00000000000000ff R15: ffff888000145000
FS: 00007f126a8eb700(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888000145000 CR3: 00000001e9a86000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
bit_clear_margins+0x3e5/0x4f0 drivers/video/fbdev/core/bitblit.c:224
fbcon_clear_margins+0x292/0x320 drivers/video/fbdev/core/fbcon.c:1317
fbcon_switch+0xd38/0x1820 drivers/video/fbdev/core/fbcon.c:2299
redraw_screen+0x335/0x7c0 drivers/tty/vt/vt.c:688
fbcon_modechanged+0x59e/0x880 drivers/video/fbdev/core/fbcon.c:2946
fbcon_event_notify+0x11f/0x17af drivers/video/fbdev/core/fbcon.c:3299
notifier_call_chain+0x111/0x1b0 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+0x80/0xa0 kernel/notifier.c:325
fb_notifier_call_chain+0x25/0x30 drivers/video/fbdev/core/fb_notify.c:45
fb_set_var+0xb09/0xcf0 drivers/video/fbdev/core/fbmem.c:1054
do_fb_ioctl+0x3cc/0x940 drivers/video/fbdev/core/fbmem.c:1127
fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1242
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007f126a8eac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 00000000200001c0 RSI: 0000000000004601 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f126a8eb6d4
R13: 00000000004c310d R14: 00000000004d83d8 R15: 00000000ffffffff
Code: d0 48 89 45 d0 41 8d 44 24 ff 89 45 c8 e8 39 d2 30 fe 8b 55 c8 45 31
ed 45 85 e4 49 8d 5c 17 01 0f 84 af 06 00 00 e8 20 d2 30 fe <45> 88 2f 49
83 c7 01 49 39 df 75 ef e8 0f d2 30 fe 48 8b 45 d0
RIP: writeb arch/x86/include/asm/io.h:65 [inline] RSP: ffff8881e9db7330
RIP: vga16fb_fillrect+0x940/0x1880 drivers/video/fbdev/vga16fb.c:923 RSP:
ffff8881e9db7330
CR2: ffff888000145000
---[ end trace 0f3fecf64584a872 ]---


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[syzbot]

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