syzbot
KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
Status:
upstream: reported C repro on 2024/12/29 01:22
Bug presence:
origin:lts-only
[Documentation on labels]
Reported-by: syzbot+e0b7d6e01c651364459a@syzkaller.appspotmail.com
First crash: 585d, last: 87d
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Bug presence (2)
| Date |
Name |
Commit |
Repro |
Result |
| 2025/01/06 |
linux-6.1.y (ToT) |
7dc732d24ff7 |
C
|
[report] KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
|
| 2025/01/06 |
upstream (ToT) |
9d89551994a4 |
C
|
Didn't crash |
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Fix bisection attempts (4)
Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
BUG: KASAN: null-ptr-deref in __refcount_add include/linux/refcount.h:193 [inline]
BUG: KASAN: null-ptr-deref in __refcount_inc include/linux/refcount.h:250 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:267 [inline]
BUG: KASAN: null-ptr-deref in get_task_struct include/linux/sched/task.h:111 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0x100/0x7f8 kernel/kthread.c:705
Write of size 4 at addr 0000000000000028 by task syz.2.133/5226
CPU: 0 PID: 5226 Comm: syz.2.133 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call trace:
dump_backtrace+0x1c0/0x1ec 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+0xf4/0x15c lib/dump_stack.c:106
print_report+0x40/0x68 mm/kasan/report.c:423
kasan_report+0xa8/0xfc mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x258/0x290 mm/kasan/generic.c:189
__kasan_check_write+0x2c/0x3c mm/kasan/shadow.c:37
instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
__refcount_add include/linux/refcount.h:193 [inline]
__refcount_inc include/linux/refcount.h:250 [inline]
refcount_inc include/linux/refcount.h:267 [inline]
get_task_struct include/linux/sched/task.h:111 [inline]
kthread_stop+0x100/0x7f8 kernel/kthread.c:705
f2fs_stop_gc_thread+0x70/0xc0 fs/f2fs/gc.c:209
f2fs_ioc_shutdown fs/f2fs/file.c:2361 [inline]
__f2fs_ioctl+0x78b4/0xb194 fs/f2fs/file.c:4373
f2fs_ioctl+0x130/0x1a0 fs/f2fs/file.c:4454
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 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
==================================================================
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
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
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001062c7000
[0000000000000028] pgd=0800000119d1f003, p4d=0800000119d1f003, pud=080000010c1de003, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5226 Comm: syz.2.133 Tainted: G B syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __lse_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic_lse.h:62 [inline]
pc : arch_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic.h:49 [inline]
pc : atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:117 [inline]
pc : __refcount_add include/linux/refcount.h:193 [inline]
pc : __refcount_inc include/linux/refcount.h:250 [inline]
pc : refcount_inc include/linux/refcount.h:267 [inline]
pc : get_task_struct include/linux/sched/task.h:111 [inline]
pc : kthread_stop+0x10c/0x7f8 kernel/kthread.c:705
lr : __lse_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic_lse.h:62 [inline]
lr : arch_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic.h:49 [inline]
lr : atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:117 [inline]
lr : __refcount_add include/linux/refcount.h:193 [inline]
lr : __refcount_inc include/linux/refcount.h:250 [inline]
lr : refcount_inc include/linux/refcount.h:267 [inline]
lr : get_task_struct include/linux/sched/task.h:111 [inline]
lr : kthread_stop+0x108/0x7f8 kernel/kthread.c:705
sp : ffff8000249d7720
x29: ffff8000249d7720 x28: ffff8000249d7960 x27: dfff800000000000
x26: 1fffe0001b88f000 x25: 0000000000400140 x24: 0000000000000000
x23: dfff800000000000 x22: dfff800000000000 x21: 0000000000000028
x20: 0000000000000001 x19: 0000000000000000 x18: ffff800011b9bf60
x17: 1fffe00033ea637e x16: ffff80000804309c x15: 0000000040000000
x14: 0000000000000001 x13: 1ffff00002fc1d6c x12: 0000000000ff0100
x11: ff00800008219508 x10: 0000000000000000 x9 : ffff800008219508
x8 : 0000000000000001 x7 : 0000000000000004 x6 : ffff800008257984
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff800008193d18
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
__lse_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic_lse.h:-1 [inline]
arch_atomic_fetch_add_relaxed arch/arm64/include/asm/atomic.h:49 [inline]
atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:117 [inline]
__refcount_add include/linux/refcount.h:193 [inline]
__refcount_inc include/linux/refcount.h:250 [inline]
refcount_inc include/linux/refcount.h:267 [inline]
get_task_struct include/linux/sched/task.h:111 [inline]
kthread_stop+0x10c/0x7f8 kernel/kthread.c:705
f2fs_stop_gc_thread+0x70/0xc0 fs/f2fs/gc.c:209
f2fs_ioc_shutdown fs/f2fs/file.c:2361 [inline]
__f2fs_ioctl+0x78b4/0xb194 fs/f2fs/file.c:4373
f2fs_ioctl+0x130/0x1a0 fs/f2fs/file.c:4454
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 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: 941b391d d503201f 940a4845 52800028 (b82802b4)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 941b391d bl 0x6ce474
4: d503201f nop
8: 940a4845 bl 0x29211c
c: 52800028 mov w8, #0x1 // #1
* 10: b82802b4 ldadd w8, w20, [x21] <-- trapping instruction
Struck through repros no longer work on HEAD.