[moderation] [raid?] BUG: unable to handle kernel paging request in free_conf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 21d6ac051080 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1359ac79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=95ac36a2cf7bfd28
dashboard link: https://syzkaller.appspot.com/bug?extid=13ca43e8b983028a0a77
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org magic...@didiglobal.com so...@kernel.org xi...@kernel.org yuk...@fnnas.com yuk...@fygo.io]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0d814dc9d616/disk-21d6ac05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a0f715272039/vmlinux-21d6ac05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/178751bdec43/Image-21d6ac05.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+13ca43...@syzkaller.appspotmail.com

__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Unable to handle kernel paging request at virtual address dfff800000000005
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0
[dfff800000000005] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] SMP
Modules linked in:
CPU: 0 UID: 0 PID: 12334 Comm: syz.5.2618 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline]
pc : raid5_has_ppl drivers/md/raid5-log.h:54 [inline]
pc : log_exit drivers/md/raid5-log.h:128 [inline]
pc : free_conf+0x88/0x540 drivers/md/raid5.c:7433
lr : free_conf+0x34/0x540 drivers/md/raid5.c:7430
sp : ffff8000932b7490
x29: ffff8000932b74a0 x28: ffff0000cd654018 x27: ffff700012656eb4
x26: ffff0000d9182000 x25: 1fffe0001b230444 x24: 0000000000000028
x23: dfff800000000000 x22: 00000000fffffff4 x21: ffff0000d9182660
x20: 0000000000000028 x19: ffff0000d9182000 x18: 1fffe00034bb7428
x17: 767265746e69202c x16: 0000000000000001 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 000000000000001f x9 : 0000000000000000
x8 : 0000000000000005 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff800080b6bae4
x2 : 0000000000000001 x1 : ffff0000f72e1d40 x0 : 0000000000000000
Call trace:
generic_test_bit include/asm-generic/bitops/generic-non-atomic.h:128 [inline] (P)
raid5_has_ppl drivers/md/raid5-log.h:54 [inline] (P)
log_exit drivers/md/raid5-log.h:128 [inline] (P)
free_conf+0x88/0x540 drivers/md/raid5.c:7433 (P)
setup_conf+0xb0c/0x1f38 drivers/md/raid5.c:7769
raid5_run+0x670/0x1b68 drivers/md/raid5.c:8013
md_run+0xb9c/0x1a6c drivers/md/md.c:6760
do_md_run+0x4c/0x4e4 drivers/md/md.c:6861
array_state_store+0x7a8/0xce8 drivers/md/md.c:-1
md_attr_store+0x304/0x438 drivers/md/md.c:6137
sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:145
kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x51c/0xa0c fs/read_write.c:687
ksys_write+0x12c/0x228 fs/read_write.c:739
__do_sys_write fs/read_write.c:750 [inline]
__se_sys_write fs/read_write.c:747 [inline]
__arm64_sys_write+0x84/0x98 fs/read_write.c:747
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Code: 97304feb f9400288 9100a114 d343fe88 (38776908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 97304feb bl 0xfffffffffcc13fac
4: f9400288 ldr x8, [x20]
8: 9100a114 add x20, x8, #0x28
c: d343fe88 lsr x8, x20, #3
* 10: 38776908 ldrb w8, [x8, x23] <-- trapping instruction


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