[v6.1] BUG: unable to handle kernel paging request in bitfill_aligned

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10e706c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=6af5de424a53c7e0070e
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7cd9b1875376/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4b5d35d18c31/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d5ee64c2af77/Image-e4f7d8be.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6af5de...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address ffff7000048f9200
KASAN: maybe wild-memory-access in range [0xffff8000247c9000-0xffff8000247c9007]
Mem abort info:
ESR = 0x0000000096000007
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x07: level 3 translation fault
Data abort info:
ISV = 0, ISS = 0x00000007
CM = 0, WnR = 0
swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000020dd2e000
[ffff7000048f9200] pgd=000000023ea48003, p4d=000000023ea48003, pud=000000023ea47003, pmd=100000010daa8003, pte=0000000000000000
Internal error: Oops: 0000000096000007 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 6529 Comm: syz.5.764 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 22400005 (nzCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : memset64+0x7c/0x118 lib/string.c:694
lr : memset_l include/linux/string.h:169 [inline]
lr : bitfill_aligned+0x16c/0x20c drivers/video/fbdev/core/sysfillrect.c:53
sp : ffff800021726e60
x29: ffff800021726e60 x28: 0000000000000180 x27: ffff8000247c9008
x26: dfff800000000000 x25: 0000000000000180 x24: 0000000000000000
x23: ffff8000247c9000 x22: 0000000000000180 x21: ffff8000247c9c00
x20: 0000000000000000 x19: ffff8000247c9000 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082dbd3c x15: 0000000000000002
x14: 0000000000000001 x13: 0000000000ff0100 x12: 0000000000080000
x11: 000000000003d6de x10: ffff800034000000 x9 : ffff80000aef73dc
x8 : 1ffff000048f9200 x7 : 0000000000000000 x6 : 0000000000000007
x5 : 0000000000000040 x4 : 0000000000006000 x3 : 0000000000000000
x2 : 0000000000000180 x1 : 0000000000000000 x0 : ffff8000247c9000
Call trace:
memset64+0x7c/0x118 lib/string.c:694
memset_l include/linux/string.h:169 [inline]
bitfill_aligned+0x16c/0x20c drivers/video/fbdev/core/sysfillrect.c:53
sys_fillrect+0x538/0x708 drivers/video/fbdev/core/sysfillrect.c:281
drm_fb_helper_sys_fillrect+0x40/0x464 drivers/gpu/drm/drm_fb_helper.c:834
drm_fbdev_fb_fillrect+0x170/0x1dc drivers/gpu/drm/drm_fb_helper.c:2384
bit_clear+0x134/0x1cc drivers/video/fbdev/core/bitblit.c:73
__fbcon_clear+0x420/0x73c drivers/video/fbdev/core/fbcon.c:1283
fbcon_scroll+0x33c/0x5ac drivers/video/fbdev/core/fbcon.c:-1
con_scroll+0x408/0x630 drivers/tty/vt/vt.c:630
csi_M+0xa8/0x144 drivers/tty/vt/vt.c:2055
do_con_trol drivers/tty/vt/vt.c:2463 [inline]
do_con_write+0x3964/0x6030 drivers/tty/vt/vt.c:2951
con_put_char+0x8c/0xd0 drivers/tty/vt/vt.c:3303
tty_put_char+0xcc/0x148 drivers/tty/tty_io.c:3140
do_output_char+0x518/0x7bc drivers/tty/n_tty.c:481
process_output drivers/tty/n_tty.c:506 [inline]
n_tty_write+0xbec/0xf50 drivers/tty/n_tty.c:2389
do_tty_write drivers/tty/tty_io.c:1018 [inline]
file_tty_write+0x3c0/0x6d8 drivers/tty/tty_io.c:1089
tty_write+0x44/0x54 drivers/tty/tty_io.c:1110
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x3c8/0x7c8 fs/read_write.c:584
ksys_write+0x12c/0x228 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 910042f7 f8010774 540001c0 d343fee8 (387a6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 910042f7 add x23, x23, #0x10
4: f8010774 str x20, [x27], #16
8: 540001c0 b.eq 0x40 // b.none
c: d343fee8 lsr x8, x23, #3
* 10: 387a6908 ldrb w8, [x8, x26] <-- trapping instruction


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