general protection fault in fbcon_fb_blanked

From: syzbot
Date: Mon Dec 09 2019 - 07:01:11 EST


Hello,

syzbot found the following crash on:

HEAD commit: eea2d5da Merge tag 'for-linus' of git://git.armlinux.org.u..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1785042ae00000
kernel config: https://syzkaller.appspot.com/x/.config?x=f07a23020fd7d21a
dashboard link: https://syzkaller.appspot.com/bug?extid=f457c8344e5a2a121e78
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+f457c8344e5a2a121e78@xxxxxxxxxxxxxxxxxxxxxxxxx

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: 12067 Comm: syz-executor.2 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fbcon_fb_blanked+0xe5/0x260 drivers/video/fbdev/core/fbcon.c:3272
Code: 0f 85 79 01 00 00 48 8d 04 db 4c 8b 3c c5 80 79 0f 8c 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 21 01 00 00
RSP: 0018:ffffc9000169fa30 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 000000000000003e RCX: ffffc9000dbd6000
RDX: 000000000000006f RSI: ffffffff83b2430a RDI: 000000000000037c
RBP: ffffc9000169fa60 R08: ffff8880a702c240 R09: ffffed10147fc003
R10: ffffc9000169fa60 R11: ffff8880a3fe0017 R12: ffff8880a3fe0000
R13: ffff8880a3f05400 R14: 0000000000000000 R15: 0000000000000000
FS: 00007fe327bd5700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000400200 CR3: 0000000058b49000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_fb_ioctl+0x18b/0x7d0 drivers/video/fbdev/core/fbmem.c:1158
fb_ioctl+0xe6/0x130 drivers/video/fbdev/core/fbmem.c:1180
vfs_ioctl fs/ioctl.c:47 [inline]
file_ioctl fs/ioctl.c:545 [inline]
do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732
ksys_ioctl+0xab/0xd0 fs/ioctl.c:749
__do_sys_ioctl fs/ioctl.c:756 [inline]
__se_sys_ioctl fs/ioctl.c:754 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
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:00007fe327bd4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6f9
RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe327bd56d4
R13: 00000000004d09d8 R14: 00000000004dc698 R15: 00000000ffffffff
Modules linked in:
---[ end trace d8165df606abdd16 ]---
RIP: 0010:fbcon_fb_blanked+0xe5/0x260 drivers/video/fbdev/core/fbcon.c:3272
Code: 0f 85 79 01 00 00 48 8d 04 db 4c 8b 3c c5 80 79 0f 8c 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 21 01 00 00
RSP: 0018:ffffc9000169fa30 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 000000000000003e RCX: ffffc9000dbd6000
RDX: 000000000000006f RSI: ffffffff83b2430a RDI: 000000000000037c
RBP: ffffc9000169fa60 R08: ffff8880a702c240 R09: ffffed10147fc003
R10: ffffc9000169fa60 R11: ffff8880a3fe0017 R12: ffff8880a3fe0000
R13: ffff8880a3f05400 R14: 0000000000000000 R15: 0000000000000000
FS: 00007fe327bd5700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa2ff0a3db8 CR3: 0000000058b49000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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