[v6.1] KASAN: user-memory-access Read in jfs_statfs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bec0e10ee67e Linux 6.1.160
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12f5e5fa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31ea1cecaf34f0db
dashboard link: https://syzkaller.appspot.com/bug?extid=49f4c1685e1a00a19b1b
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=160f299a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0c7c6a53ac77/disk-bec0e10e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/38567d4ccc5b/vmlinux-bec0e10e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5f0a7945f428/Image-bec0e10e.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1ff29ef4b56b/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=177939fc580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+49f4c1...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: user-memory-access in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: user-memory-access in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: user-memory-access in jfs_statfs+0x1f8/0x484 fs/jfs/super.c:140
Read of size 4 at addr 00000000000050c0 by task syz.2.38/4584

CPU: 1 PID: 4584 Comm: syz.2.38 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack+0x30/0x40 lib/dump_stack.c:88
dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
print_report+0x40/0x68 mm/kasan/report.c:423
kasan_report+0xa8/0x100 mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x260/0x2a0 mm/kasan/generic.c:189
__kasan_check_read+0x2c/0x3c mm/kasan/shadow.c:31
instrument_atomic_read include/linux/instrumented.h:72 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
jfs_statfs+0x1f8/0x484 fs/jfs/super.c:140
statfs_by_dentry fs/statfs.c:66 [inline]
vfs_statfs fs/statfs.c:90 [inline]
user_statfs+0x1bc/0x4f0 fs/statfs.c:105
__do_sys_statfs fs/statfs.c:195 [inline]
__se_sys_statfs fs/statfs.c:192 [inline]
__arm64_sys_statfs+0xc8/0x148 fs/statfs.c:192
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 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
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000a18
KASAN: probably user-memory-access in range [0x00000000000050c0-0x00000000000050c7]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000a18] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4584 Comm: syz.2.38 Tainted: G B syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : atomic_read include/linux/atomic/atomic-instrumented.h:28 [inline]
pc : jfs_statfs+0x1fc/0x484 fs/jfs/super.c:140
lr : instrument_atomic_read include/linux/instrumented.h:72 [inline]
lr : atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
lr : jfs_statfs+0x1f8/0x484 fs/jfs/super.c:140
sp : ffff800021297b30
x29: ffff800021297b40 x28: 0000000000000a18 x27: 1fffe0001a0e5b94
x26: 0000000000005000 x25: 0000000000000000 x24: ffff0000ea04d108
x23: dfff800000000000 x22: ffff800021297ca0 x21: ffff0000d072dca0
x20: 00000000000050c0 x19: ffff800021297c80 x18: ffff800011a6bd40
x17: 0000000000000000 x16: ffff800008042d90 x15: 0000000000000000
x14: 00000000ffffffff x13: 0000000000000001 x12: 0000000000ff0100
x11: ff00800008191fd0 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000212974f8 x4 : ffff800015134e80 x3 : ffff800008191f94
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
atomic_read include/linux/atomic/atomic-instrumented.h:28 [inline]
jfs_statfs+0x1fc/0x484 fs/jfs/super.c:140
statfs_by_dentry fs/statfs.c:66 [inline]
vfs_statfs fs/statfs.c:90 [inline]
user_statfs+0x1bc/0x4f0 fs/statfs.c:105
__do_sys_statfs fs/statfs.c:195 [inline]
__se_sys_statfs fs/statfs.c:192 [inline]
__arm64_sys_statfs+0xc8/0x148 fs/statfs.c:192
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 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: 52800081 aa1403e0 97c24fed d343fe9c (38f76b88)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 52800081 mov w1, #0x4 // #4
4: aa1403e0 mov x0, x20
8: 97c24fed bl 0xffffffffff093fbc
c: d343fe9c lsr x28, x20, #3
* 10: 38f76b88 ldrsb w8, [x28, x23] <-- trapping instruction


---
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