Re: [syzbot] BUG: unable to handle kernel paging request in bitfill_aligned (2)

From: syzbot
Date: Thu Dec 09 2021 - 13:25:22 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 2a987e65025e Merge tag 'perf-tools-fixes-for-v5.16-2021-12..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f8fdc5b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7d5e878e3399b6cc
dashboard link: https://syzkaller.appspot.com/bug?extid=a4edd73d589b0b7efbeb
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16671badb00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122beabdb00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4edd73d589b0b7efbeb@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: unable to handle page fault for address: ffff888001000030
#PF: supervisor write access in kernel mode
#PF: error_code(0x0003) - permissions violation
PGD 11201067 P4D 11201067 PUD 11202067 PMD 80000000010001e1
Oops: 0003 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6524 Comm: syz-executor260 Not tainted 5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__writeq arch/x86/include/asm/io.h:98 [inline]
RIP: 0010:bitfill_aligned+0x1d2/0x270 drivers/video/fbdev/core/cfbfillrect.c:75
Code: 39 1b fd eb 09 e8 3e 39 1b fd 48 83 c3 40 31 ff 89 ee e8 41 3d 1b fd 85 ed 74 2c 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 ff cd <4c> 89 33 85 ed 74 0b 48 83 c3 08 e8 0e 39 1b fd eb ec e8 07 39 1b
RSP: 0018:ffffc90002b4ee38 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff888001000030 RCX: ffff888020209d00
RDX: ffff888020209d00 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff84695e4f R09: 0000000000000040
R10: 0000000000000002 R11: ffff888020209d00 R12: ffffffffffffffff
R13: 0000000000000080 R14: 0000000000000000 R15: 0000000000000000
FS: 0000555555c14300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888001000030 CR3: 00000000708fb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
cfb_fillrect+0x5d8/0x800 drivers/video/fbdev/core/cfbfillrect.c:327
bit_clear_margins+0x2d7/0x6e0 drivers/video/fbdev/core/bitblit.c:209
fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1296 [inline]
fbcon_switch+0x1569/0x21f0 drivers/video/fbdev/core/fbcon.c:1677
redraw_screen+0x53d/0x1280 drivers/tty/vt/vt.c:1021
vc_do_resize+0x1361/0x1930 drivers/tty/vt/vt.c:1342
fbcon_do_set_font+0x9ef/0x10d0 drivers/video/fbdev/core/fbcon.c:1928
fbcon_set_font+0x9f9/0xc80 drivers/video/fbdev/core/fbcon.c:2014
con_font_set drivers/tty/vt/vt.c:4666 [inline]
con_font_op+0xbcd/0x1080 drivers/tty/vt/vt.c:4710
vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
vt_ioctl+0x1838/0x3860 drivers/tty/vt/vt_ioctl.c:752
tty_ioctl+0xfb2/0x17d0 drivers/tty/tty_io.c:2805
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f44f1232229
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffb8c823a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f44f1232229
RDX: 0000000020000400 RSI: 0000000000004b72 RDI: 0000000000000004
RBP: 0000000000000000 R08: 000000000000000d R09: 00007fffb8c82548
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f44f11f5820
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
CR2: ffff888001000030
---[ end trace 3cf2fa8eab0f5f7d ]---
RIP: 0010:__writeq arch/x86/include/asm/io.h:98 [inline]
RIP: 0010:bitfill_aligned+0x1d2/0x270 drivers/video/fbdev/core/cfbfillrect.c:75
Code: 39 1b fd eb 09 e8 3e 39 1b fd 48 83 c3 40 31 ff 89 ee e8 41 3d 1b fd 85 ed 74 2c 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 ff cd <4c> 89 33 85 ed 74 0b 48 83 c3 08 e8 0e 39 1b fd eb ec e8 07 39 1b
RSP: 0018:ffffc90002b4ee38 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff888001000030 RCX: ffff888020209d00
RDX: ffff888020209d00 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff84695e4f R09: 0000000000000040
R10: 0000000000000002 R11: ffff888020209d00 R12: ffffffffffffffff
R13: 0000000000000080 R14: 0000000000000000 R15: 0000000000000000
FS: 0000555555c14300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888001000030 CR3: 00000000708fb000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 39 1b cmp %ebx,(%rbx)
2: fd std
3: eb 09 jmp 0xe
5: e8 3e 39 1b fd callq 0xfd1b3948
a: 48 83 c3 40 add $0x40,%rbx
e: 31 ff xor %edi,%edi
10: 89 ee mov %ebp,%esi
12: e8 41 3d 1b fd callq 0xfd1b3d58
17: 85 ed test %ebp,%ebp
19: 74 2c je 0x47
1b: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1)
22: 00 00 00
25: 0f 1f 00 nopl (%rax)
28: ff cd dec %ebp
* 2a: 4c 89 33 mov %r14,(%rbx) <-- trapping instruction
2d: 85 ed test %ebp,%ebp
2f: 74 0b je 0x3c
31: 48 83 c3 08 add $0x8,%rbx
35: e8 0e 39 1b fd callq 0xfd1b3948
3a: eb ec jmp 0x28
3c: e8 .byte 0xe8
3d: 07 (bad)
3e: 39 1b cmp %ebx,(%rbx)