syzbot

 sign-in | mailing list | source | docs
🐞 Open [119]
🐞 Fixed [69]
🐞 Invalid [267]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

KASAN: null-ptr-deref Write in f2fs_issue_flush

Status: upstream: reported C repro on 2025/11/09 06:59
Reported-by: syzbot+f3175bdf7b93966197b4@syzkaller.appspotmail.com
First crash: 63d, last: 16d
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: null-ptr-deref Write in f2fs_issue_flush origin:lts 12 C error 4 18d 103d 0/2 upstream: reported C repro on 2025/09/30 19:35
linux-6.1 KASAN: null-ptr-deref Write in f2fs_issue_flush origin:lts-only 12 C 3 29d 102d 0/3 upstream: reported C repro on 2025/10/01 01:02
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2025/11/25 22:59 9m retest repro android13-5.10-lts report log
2025/11/25 22:59 11m retest repro android13-5.10-lts report log
2025/11/25 22:59 12m retest repro android13-5.10-lts report log
2025/11/25 22:59 9m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2025/12/26 01:51 2h14m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
F2FS-fs (loop2): Mounted with checkpoint version = 48b305e5
======================================================
WARNING: the mand mount option is being deprecated and
         will be removed in v5.15!
======================================================
F2FS-fs (loop2): Try to recover all the superblocks, ret: 0
==================================================================
BUG: KASAN: null-ptr-deref in f2fs_issue_flush+0x14c/0x890 fs/f2fs/segment.c:-1
Write of size 4 at addr 0000000000000024 by task syz.2.17/381

CPU: 1 PID: 381 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:439 [inline]
 kasan_report+0xd8/0x130 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 f2fs_issue_flush+0x14c/0x890 fs/f2fs/segment.c:-1
 f2fs_do_sync_file+0x1293/0x1cf0 fs/f2fs/file.c:385
 f2fs_ioc_commit_atomic_write fs/f2fs/file.c:2192 [inline]
 __f2fs_ioctl+0x3fa2/0xca50 fs/f2fs/file.c:4335
 f2fs_ioctl+0x149/0x240 fs/f2fs/file.c:4428
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f5629dee6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc74cf70f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f562a044fa0 RCX: 00007f5629dee6c9
RDX: 0000000000000000 RSI: 000000000000f502 RDI: 0000000000000005
RBP: 00007f5629e70f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f562a044fa0 R14: 00007f562a044fa0 R15: 0000000000000003
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000024
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 129a99067 P4D 129a99067 PUD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 381 Comm: syz.2.17 Tainted: G    B             syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:arch_atomic_inc fs/f2fs/segment.c:-1 [inline]
RIP: 0010:atomic_inc include/asm-generic/atomic-instrumented.h:241 [inline]
RIP: 0010:f2fs_issue_flush+0x15d/0x890 fs/f2fs/segment.c:678
Code: c2 5a ff 4c 89 64 24 28 49 83 c4 24 4c 89 e7 be 04 00 00 00 e8 14 b0 94 ff 81 e3 00 04 00 00 0f 85 52 01 00 00 4c 89 64 24 08 <f0> 41 ff 04 24 4c 8b 74 24 20 4d 8d ae 6c 0c 00 00 4d 89 ec 49 c1
RSP: 0018:ffffc9000433f620 EFLAGS: 00010246
RAX: ffff88810cac8000 RBX: 0000000000000000 RCX: 0000000000000282
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000ffffffff
RBP: ffffc9000433f730 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8ee48 R11: 1ffffffff0d8ee48 R12: 0000000000000024
R13: ffffc9000433f680 R14: 0000000000000000 R15: 1ffff92000867ecc
FS:  00005555798a6500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000024 CR3: 000000010efed000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 f2fs_do_sync_file+0x1293/0x1cf0 fs/f2fs/file.c:385
 f2fs_ioc_commit_atomic_write fs/f2fs/file.c:2192 [inline]
 __f2fs_ioctl+0x3fa2/0xca50 fs/f2fs/file.c:4335
 f2fs_ioctl+0x149/0x240 fs/f2fs/file.c:4428
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f5629dee6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc74cf70f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f562a044fa0 RCX: 00007f5629dee6c9
RDX: 0000000000000000 RSI: 000000000000f502 RDI: 0000000000000005
RBP: 00007f5629e70f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f562a044fa0 R14: 00007f562a044fa0 R15: 0000000000000003
Modules linked in:
CR2: 0000000000000024
---[ end trace 0a3b7e7e7e0f1ded ]---
RIP: 0010:arch_atomic_inc fs/f2fs/segment.c:-1 [inline]
RIP: 0010:atomic_inc include/asm-generic/atomic-instrumented.h:241 [inline]
RIP: 0010:f2fs_issue_flush+0x15d/0x890 fs/f2fs/segment.c:678
Code: c2 5a ff 4c 89 64 24 28 49 83 c4 24 4c 89 e7 be 04 00 00 00 e8 14 b0 94 ff 81 e3 00 04 00 00 0f 85 52 01 00 00 4c 89 64 24 08 <f0> 41 ff 04 24 4c 8b 74 24 20 4d 8d ae 6c 0c 00 00 4d 89 ec 49 c1
RSP: 0018:ffffc9000433f620 EFLAGS: 00010246
RAX: ffff88810cac8000 RBX: 0000000000000000 RCX: 0000000000000282
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 00000000ffffffff
RBP: ffffc9000433f730 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff0d8ee48 R11: 1ffffffff0d8ee48 R12: 0000000000000024
R13: ffffc9000433f680 R14: 0000000000000000 R15: 1ffff92000867ecc
FS:  00005555798a6500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000024 CR3: 000000010efed000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	c2 5a ff             	ret    $0xff5a
   3:	4c 89 64 24 28       	mov    %r12,0x28(%rsp)
   8:	49 83 c4 24          	add    $0x24,%r12
   c:	4c 89 e7             	mov    %r12,%rdi
   f:	be 04 00 00 00       	mov    $0x4,%esi
  14:	e8 14 b0 94 ff       	call   0xff94b02d
  19:	81 e3 00 04 00 00    	and    $0x400,%ebx
  1f:	0f 85 52 01 00 00    	jne    0x177
  25:	4c 89 64 24 08       	mov    %r12,0x8(%rsp)
* 2a:	f0 41 ff 04 24       	lock incl (%r12) <-- trapping instruction
  2f:	4c 8b 74 24 20       	mov    0x20(%rsp),%r14
  34:	4d 8d ae 6c 0c 00 00 	lea    0xc6c(%r14),%r13
  3b:	4d 89 ec             	mov    %r13,%r12
  3e:	49                   	rex.WB
  3f:	c1                   	.byte 0xc1

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/11 21:18 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .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_issue_flush
2025/11/11 18:27 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .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_issue_flush
2025/11/09 07:10 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .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_issue_flush
2025/11/09 06:50 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .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_issue_flush
2025/11/09 06:29 android13-5.10-lts ab3e1c0dd1ff 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: null-ptr-deref Write in f2fs_issue_flush
* Struck through repros no longer work on HEAD.