syzbot


KASAN: user-memory-access Read in jfs_statfs

Status: upstream: reported syz repro on 2026/01/12 17:59
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+49f4c1685e1a00a19b1b@syzkaller.appspotmail.com
First crash: 6d08h, last: 6d08h
Bug presence (1)
Date Name Commit Repro Result
2026/01/13 upstream (ToT) b54345928fa1 syz [report] KASAN: user-memory-access Read in jfs_statfs
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: user-memory-access Read in jfs_statfs jfs 17 C unreliable error 12 25d 621d 0/29 upstream: reported C repro on 2024/05/07 07:57

Sample crash report:
==================================================================
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

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/12 17:58 linux-6.1.y bec0e10ee67e d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 KASAN: user-memory-access Read in jfs_statfs
* Struck through repros no longer work on HEAD.