Re: [syzbot] BUG: unable to handle kernel paging request in bitfill_aligned (3)

From: syzbot
Date: Sat Aug 13 2022 - 09:12:33 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 7ebfc85e2cd7 Merge tag 'net-6.0-rc1' of git://git.kernel.o..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=179c3aa5080000
kernel config: https://syzkaller.appspot.com/x/.config?x=20bc0b329895d963
dashboard link: https://syzkaller.appspot.com/bug?extid=a168dbeaaa7778273c1b
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16e0ef4b080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11a1183d080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a168dbeaaa7778273c1b@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: unable to handle page fault for address: ffffc900043a1000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 12000067 P4D 12000067 PUD 121c9067 PMD 14733a067 PTE 0
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3633 Comm: syz-executor339 Not tainted 5.19.0-syzkaller-13930-g7ebfc85e2cd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
RIP: 0010:memset64 arch/x86/include/asm/string_64.h:49 [inline]
RIP: 0010:memset_l include/linux/string.h:128 [inline]
RIP: 0010:bitfill_aligned+0x1ad/0x270 drivers/video/fbdev/core/sysfillrect.c:53
Code: 08 49 31 ef eb 66 e8 52 38 03 fd 45 89 e6 4c 8b 64 24 10 44 89 f0 31 d2 f7 f3 89 c3 48 8b 6c 24 08 48 89 e8 4c 89 e7 48 89 d9 <f3> 48 ab 31 ff 44 89 ee e8 46 3c 03 fd 4d 85 ed 74 5f 4d 8d 24 dc
RSP: 0018:ffffc90003a6f7e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000ffc RCX: 00000000000001fc
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc900043a1000
RBP: 0000000000000000 R08: ffffffff848659ae R09: 0000000000000040
R10: 0000000000000002 R11: ffff888021ffd880 R12: ffffc9000439a000
R13: 0000000000000000 R14: 000000000003ff00 R15: ffffffffffffffff
FS: 0000555556df7300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc900043a1000 CR3: 0000000072ba0000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
sys_fillrect+0x5ce/0x7f0 drivers/video/fbdev/core/sysfillrect.c:281
drm_fb_helper_sys_fillrect drivers/gpu/drm/drm_fb_helper.c:807 [inline]
drm_fbdev_fb_fillrect+0x163/0x300 drivers/gpu/drm/drm_fb_helper.c:2322
bit_clear_margins+0x3f1/0x6e0 drivers/video/fbdev/core/bitblit.c:232
fbcon_clear_margins drivers/video/fbdev/core/fbcon.c:1306 [inline]
fbcon_do_set_font+0xd7c/0x1330 drivers/video/fbdev/core/fbcon.c:2431
fbcon_set_font+0xc29/0xf70 drivers/video/fbdev/core/fbcon.c:2519
con_font_set drivers/tty/vt/vt.c:4666 [inline]
con_font_op+0xbe8/0x1070 drivers/tty/vt/vt.c:4710
vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
vt_ioctl+0x172e/0x1d00 drivers/tty/vt/vt_ioctl.c:752
tty_ioctl+0x874/0xc60 drivers/tty/tty_io.c:2778
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7efe5924e239
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:00007fffba970648 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007efe5924e239
RDX: 0000000020000000 RSI: 0000000000004b72 RDI: 0000000000000004
RBP: 00007fffba970660 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 00007fffba97065c R14: 00007fffba970680 R15: 00007fffba970670
</TASK>
Modules linked in:
CR2: ffffc900043a1000
---[ end trace 0000000000000000 ]---
RIP: 0010:memset64 arch/x86/include/asm/string_64.h:49 [inline]
RIP: 0010:memset_l include/linux/string.h:128 [inline]
RIP: 0010:bitfill_aligned+0x1ad/0x270 drivers/video/fbdev/core/sysfillrect.c:53
Code: 08 49 31 ef eb 66 e8 52 38 03 fd 45 89 e6 4c 8b 64 24 10 44 89 f0 31 d2 f7 f3 89 c3 48 8b 6c 24 08 48 89 e8 4c 89 e7 48 89 d9 <f3> 48 ab 31 ff 44 89 ee e8 46 3c 03 fd 4d 85 ed 74 5f 4d 8d 24 dc
RSP: 0018:ffffc90003a6f7e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000ffc RCX: 00000000000001fc
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc900043a1000
RBP: 0000000000000000 R08: ffffffff848659ae R09: 0000000000000040
R10: 0000000000000002 R11: ffff888021ffd880 R12: ffffc9000439a000
R13: 0000000000000000 R14: 000000000003ff00 R15: ffffffffffffffff
FS: 0000555556df7300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc900043a1000 CR3: 0000000072ba0000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 08 49 31 or %cl,0x31(%rcx)
3: ef out %eax,(%dx)
4: eb 66 jmp 0x6c
6: e8 52 38 03 fd callq 0xfd03385d
b: 45 89 e6 mov %r12d,%r14d
e: 4c 8b 64 24 10 mov 0x10(%rsp),%r12
13: 44 89 f0 mov %r14d,%eax
16: 31 d2 xor %edx,%edx
18: f7 f3 div %ebx
1a: 89 c3 mov %eax,%ebx
1c: 48 8b 6c 24 08 mov 0x8(%rsp),%rbp
21: 48 89 e8 mov %rbp,%rax
24: 4c 89 e7 mov %r12,%rdi
27: 48 89 d9 mov %rbx,%rcx
* 2a: f3 48 ab rep stos %rax,%es:(%rdi) <-- trapping instruction
2d: 31 ff xor %edi,%edi
2f: 44 89 ee mov %r13d,%esi
32: e8 46 3c 03 fd callq 0xfd033c7d
37: 4d 85 ed test %r13,%r13
3a: 74 5f je 0x9b
3c: 4d 8d 24 dc lea (%r12,%rbx,8),%r12