syzbot


KASAN: null-ptr-deref Write in f2fs_stop_gc_thread

Status: upstream: reported C repro on 2025/04/02 05:33
Reported-by: syzbot+29fcdc1e1210dbbec4f5@syzkaller.appspotmail.com
First crash: 2d22h, last: 2d01h
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: null-ptr-deref Write in f2fs_stop_gc_thread f2fs C done 5 207d 254d 28/28 fixed on 2024/10/22 11:56
linux-6.1 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread origin:lts-only C error 10 88d 96d 0/3 upstream: reported C repro on 2024/12/29 01:22

Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [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:108 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0x3b/0x410 kernel/kthread.c:640
Write of size 4 at addr 0000000000000020 by task syz-executor258/9526

CPU: 1 PID: 9526 Comm: syz-executor258 Not tainted 5.10.234-syzkaller-00033-g094fc3778d6b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:439 [inline]
 kasan_report+0x167/0x1c0 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [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:108 [inline]
 kthread_stop+0x3b/0x410 kernel/kthread.c:640
 f2fs_stop_gc_thread+0x65/0xb0 fs/f2fs/gc.c:199
 f2fs_ioc_shutdown fs/f2fs/file.c:2361 [inline]
 __f2fs_ioctl+0x7830/0xda80 fs/f2fs/file.c:4330
 f2fs_ioctl+0x170/0x550 fs/f2fs/file.c:4415
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x114/0x190 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x34/0x70 arch/x86/entry/common.c:-1
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f2233842409
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f22337dd168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f22338cf6d8 RCX: 00007f2233842409
RDX: 0000200000000140 RSI: 000000008004587d RDI: 0000000000000005
RBP: 00007f22338cf6d0 R08: 00007f22337dd6c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f22338cf6dc
R13: 000000000000006e R14: 00007ffd06d9cef0 R15: 00007ffd06d9cfd8
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000020
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9526 Comm: syz-executor258 Tainted: G    B             5.10.234-syzkaller-00033-g094fc3778d6b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:arch_atomic_fetch_add include/linux/instrumented.h:-1 [inline]
RIP: 0010:atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:143 [inline]
RIP: 0010:__refcount_add include/linux/refcount.h:193 [inline]
RIP: 0010:__refcount_inc include/linux/refcount.h:250 [inline]
RIP: 0010:refcount_inc include/linux/refcount.h:267 [inline]
RIP: 0010:get_task_struct include/linux/sched/task.h:108 [inline]
RIP: 0010:kthread_stop+0x40/0x410 kernel/kthread.c:640
Code: 00 fc ff df e8 31 26 24 00 0f 1f 44 00 00 e8 27 26 24 00 4d 8d 74 24 20 4c 89 f7 be 04 00 00 00 e8 55 c7 61 00 bb 01 00 00 00 <f0> 41 0f c1 5c 24 20 31 ff 89 de e8 b0 29 24 00 85 db 0f 84 2f 01
RSP: 0018:ffffc90007c87838 EFLAGS: 00010246
RAX: ffff8881104d8000 RBX: 0000000000000001 RCX: ffff8881104d8000
RDX: 0000000000000000 RSI: 0000000000000282 RDI: 00000000ffffffff
RBP: ffffc90007c87860 R08: ffffffff813e2b8b R09: 0000000000000003
R10: fffffbfff0e11248 R11: dffffc0000000001 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000020 R15: dffffc0000000000
FS:  00007f22337dd6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 00000001172e2000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 f2fs_stop_gc_thread+0x65/0xb0 fs/f2fs/gc.c:199
 f2fs_ioc_shutdown fs/f2fs/file.c:2361 [inline]
 __f2fs_ioctl+0x7830/0xda80 fs/f2fs/file.c:4330
 f2fs_ioctl+0x170/0x550 fs/f2fs/file.c:4415
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x114/0x190 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x34/0x70 arch/x86/entry/common.c:-1
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f2233842409
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f22337dd168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f22338cf6d8 RCX: 00007f2233842409
RDX: 0000200000000140 RSI: 000000008004587d RDI: 0000000000000005
RBP: 00007f22338cf6d0 R08: 00007f22337dd6c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f22338cf6dc
R13: 000000000000006e R14: 00007ffd06d9cef0 R15: 00007ffd06d9cfd8
Modules linked in:
CR2: 0000000000000020
---[ end trace 548e7fcf217f0a3d ]---
RIP: 0010:arch_atomic_fetch_add include/linux/instrumented.h:-1 [inline]
RIP: 0010:atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:143 [inline]
RIP: 0010:__refcount_add include/linux/refcount.h:193 [inline]
RIP: 0010:__refcount_inc include/linux/refcount.h:250 [inline]
RIP: 0010:refcount_inc include/linux/refcount.h:267 [inline]
RIP: 0010:get_task_struct include/linux/sched/task.h:108 [inline]
RIP: 0010:kthread_stop+0x40/0x410 kernel/kthread.c:640
Code: 00 fc ff df e8 31 26 24 00 0f 1f 44 00 00 e8 27 26 24 00 4d 8d 74 24 20 4c 89 f7 be 04 00 00 00 e8 55 c7 61 00 bb 01 00 00 00 <f0> 41 0f c1 5c 24 20 31 ff 89 de e8 b0 29 24 00 85 db 0f 84 2f 01
RSP: 0018:ffffc90007c87838 EFLAGS: 00010246
RAX: ffff8881104d8000 RBX: 0000000000000001 RCX: ffff8881104d8000
RDX: 0000000000000000 RSI: 0000000000000282 RDI: 00000000ffffffff
RBP: ffffc90007c87860 R08: ffffffff813e2b8b R09: 0000000000000003
R10: fffffbfff0e11248 R11: dffffc0000000001 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000020 R15: dffffc0000000000
FS:  00007f22337dd6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 00000001172e2000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 3 bytes skipped:
   0:	df e8                	fucomip %st(0),%st
   2:	31 26                	xor    %esp,(%rsi)
   4:	24 00                	and    $0x0,%al
   6:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
   b:	e8 27 26 24 00       	call   0x242637
  10:	4d 8d 74 24 20       	lea    0x20(%r12),%r14
  15:	4c 89 f7             	mov    %r14,%rdi
  18:	be 04 00 00 00       	mov    $0x4,%esi
  1d:	e8 55 c7 61 00       	call   0x61c777
  22:	bb 01 00 00 00       	mov    $0x1,%ebx
* 27:	f0 41 0f c1 5c 24 20 	lock xadd %ebx,0x20(%r12) <-- trapping instruction
  2e:	31 ff                	xor    %edi,%edi
  30:	89 de                	mov    %ebx,%esi
  32:	e8 b0 29 24 00       	call   0x2429e7
  37:	85 db                	test   %ebx,%ebx
  39:	0f                   	.byte 0xf
  3a:	84 2f                	test   %ch,(%rdi)
  3c:	01                   	.byte 0x1

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/02 20:28 android13-5.10-lts 094fc3778d6b c799dfdd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
2025/04/02 09:59 android13-5.10-lts 094fc3778d6b c799dfdd .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
2025/04/02 05:23 android13-5.10-lts 094fc3778d6b b8645499 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
2025/04/02 23:07 android13-5.10-lts 094fc3778d6b c799dfdd .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
2025/04/02 01:54 android13-5.10-lts 094fc3778d6b b8645499 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_stop_gc_thread
* Struck through repros no longer work on HEAD.