syzbot
BUG: unable to handle kernel paging request in bitfill_aligned
Status:
upstream: reported on 2026/08/15 01:29
Reported-by: syzbot+6af5de424a53c7e0070e@syzkaller.appspotmail.com
First crash: 6d01h, last: 2d22h
Sample crash report:
BUG: unable to handle page fault for address: ffffc900046b9000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 17400067 P4D 17400067 PUD 17622067 PMD 248e3067 PTE 0
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 16999 Comm: syz.4.2547 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:memset64 arch/x86/include/asm/string_64.h:64 [inline]
RIP: 0010:memset_l include/linux/string.h:169 [inline]
RIP: 0010:bitfill_aligned+0x18e/0x230 drivers/video/fbdev/core/sysfillrect.c:53
Code: 48 31 c3 49 89 1e eb 73 e8 af d8 2c fd 44 89 e3 4c 8b 64 24 08 4c 8b 2c 24 89 d8 31 d2 f7 f5 89 c3 4c 89 e0 4c 89 ef 48 89 d9 <f3> 48 ab 31 ff 44 89 fe e8 e5 db 2c fd 4d 85 ff 74 3a e8 7b d8 2c
RSP: 0018:ffffc900036672e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 000000000000017a RCX: 000000000000017a
RDX: 0000000000000000 RSI: 00000000000130ac RDI: ffffc900046b9000
RBP: 0000000000000040 R08: 0000000000005e80 R09: 0000000000000040
R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000000
R13: ffffc900046b9000 R14: ffffffffffffffff R15: 0000000000000000
FS: 00007fbc808396c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc900046b9000 CR3: 00000000285ab000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
sys_fillrect+0x5e0/0x7d0 drivers/video/fbdev/core/sysfillrect.c:281
drm_fb_helper_sys_fillrect+0x2e/0x510 drivers/gpu/drm/drm_fb_helper.c:834
bit_clear+0x15f/0x1f0 drivers/video/fbdev/core/bitblit.c:73
__fbcon_clear+0x4c3/0x820 drivers/video/fbdev/core/fbcon.c:1283
fbcon_scroll+0x43e/0x760 drivers/video/fbdev/core/fbcon.c:1851
con_scroll+0x50e/0x7a0 drivers/tty/vt/vt.c:630
csi_M+0xa8/0x140 drivers/tty/vt/vt.c:2055
do_con_trol drivers/tty/vt/vt.c:2463 [inline]
do_con_write+0x4289/0x6c40 drivers/tty/vt/vt.c:2951
con_write+0x1f/0x40 drivers/tty/vt/vt.c:3295
process_output_block drivers/tty/n_tty.c:586 [inline]
n_tty_write+0xd61/0x11e0 drivers/tty/n_tty.c:2377
do_tty_write drivers/tty/tty_io.c:1018 [inline]
file_tty_write+0x4c7/0x840 drivers/tty/tty_io.c:1089
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x482/0x9a0 fs/read_write.c:584
ksys_write+0x14d/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fbc7f99e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc80839028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fbc7fc26180 RCX: 00007fbc7f99e0d9
RDX: 0000000000001006 RSI: 0000200000000000 RDI: 0000000000000008
RBP: 00007fbc7fa35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc7fc26218 R14: 00007fbc7fc26180 R15: 00007ffc903699a8
</TASK>
Modules linked in:
CR2: ffffc900046b9000
---[ end trace 0000000000000000 ]---
RIP: 0010:memset64 arch/x86/include/asm/string_64.h:64 [inline]
RIP: 0010:memset_l include/linux/string.h:169 [inline]
RIP: 0010:bitfill_aligned+0x18e/0x230 drivers/video/fbdev/core/sysfillrect.c:53
Code: 48 31 c3 49 89 1e eb 73 e8 af d8 2c fd 44 89 e3 4c 8b 64 24 08 4c 8b 2c 24 89 d8 31 d2 f7 f5 89 c3 4c 89 e0 4c 89 ef 48 89 d9 <f3> 48 ab 31 ff 44 89 fe e8 e5 db 2c fd 4d 85 ff 74 3a e8 7b d8 2c
RSP: 0018:ffffc900036672e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 000000000000017a RCX: 000000000000017a
RDX: 0000000000000000 RSI: 00000000000130ac RDI: ffffc900046b9000
RBP: 0000000000000040 R08: 0000000000005e80 R09: 0000000000000040
R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000000
R13: ffffc900046b9000 R14: ffffffffffffffff R15: 0000000000000000
FS: 00007fbc808396c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc900046b9000 CR3: 00000000285ab000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 31 c3 xor %rax,%rbx
3: 49 89 1e mov %rbx,(%r14)
6: eb 73 jmp 0x7b
8: e8 af d8 2c fd call 0xfd2cd8bc
d: 44 89 e3 mov %r12d,%ebx
10: 4c 8b 64 24 08 mov 0x8(%rsp),%r12
15: 4c 8b 2c 24 mov (%rsp),%r13
19: 89 d8 mov %ebx,%eax
1b: 31 d2 xor %edx,%edx
1d: f7 f5 div %ebp
1f: 89 c3 mov %eax,%ebx
21: 4c 89 e0 mov %r12,%rax
24: 4c 89 ef mov %r13,%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 fe mov %r15d,%esi
32: e8 e5 db 2c fd call 0xfd2cdc1c
37: 4d 85 ff test %r15,%r15
3a: 74 3a je 0x76
3c: e8 .byte 0xe8
3d: 7b d8 jnp 0x17
3f: 2c .byte 0x2c
* Struck through repros no longer work on HEAD.