syzbot


KASAN: null-ptr-deref Write in incfs_kill_sb (2)

Status: premoderation: reported on 2026/07/05 07:33
Reported-by: syzbot+1ee77ac9f3b994fa8809@syzkaller.appspotmail.com
First crash: 7d19h, last: 7d19h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: null-ptr-deref Write in incfs_kill_sb 12 3 26d 71d 0/2 premoderation: reported on 2026/05/02 13:38
android-5-10 KASAN: null-ptr-deref Write in incfs_kill_sb 12 1 270d 270d 0/2 auto-obsoleted due to no activity on 2026/01/14 00:20
android-5-10 general protection fault in incfs_kill_sb 2 C done 380 1598d 1600d 2/2 fixed on 2022/05/12 07:47
android-54 general protection fault in incfs_kill_sb 2 C 2965 1585d 1619d 2/2 fixed on 2022/04/19 10:20

Sample crash report:
R13: 00007f90c6f872ca R14: 000000000001056c R15: 00007fff413f52d0
---[ end trace 5458fae90bc57b21 ]---
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_inc_return include/asm-generic/atomic-instrumented.h:250 [inline]
BUG: KASAN: null-ptr-deref in ihold+0x20/0x60 fs/inode.c:423
Write of size 4 at addr 0000000000000170 by task syz-executor/284

CPU: 0 PID: 284 Comm: syz-executor Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:439 [inline]
 kasan_report+0xbd/0x140 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37
 incfs_kill_sb+0xf7/0x200 fs/incfs/vfs.c:1973
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130
 task_work_run+0x127/0x190 kernel/task_work.c:189
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
Code: a2 c7 05 5c 26 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff413f4148 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f90c6ef3097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff413f4200
RBP: 00007fff413f4200 R08: 00007fff413f5200 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff413f5290
R13: 00007f90c6f872ca R14: 000000000001056c R15: 00007fff413f52d0
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000170
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 10af46067 
P4D 10af46067 
PUD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 284 Comm: syz-executor Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:165 [inline]
RIP: 0010:arch_atomic_inc_return include/linux/atomic-arch-fallback.h:286 [inline]
RIP: 0010:atomic_inc_return include/asm-generic/atomic-instrumented.h:251 [inline]
RIP: 0010:ihold+0x26/0x60 fs/inode.c:423
Code: 00 00 00 00 55 48 89 e5 41 56 53 48 89 fb e8 b1 7d b7 ff 48 8d bb 70 01 00 00 be 04 00 00 00 e8 a0 f5 f1 ff 41 be 01 00 00 00 <f0> 44 0f c1 b3 70 01 00 00 41 ff c6 bf 02 00 00 00 44 89 f6 e8 31
RSP: 0018:ffffc90000c07d38 EFLAGS: 00010246
RAX: ffff88811e68e200 RBX: 0000000000000000 RCX: ffff88811e68e2c0
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 00000000ffffffff
RBP: ffffc90000c07d48 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf648 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
FS:  0000555576f19500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000170 CR3: 0000000126811000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 d_delete_notify include/linux/fsnotify.h:264 [inline]
 vfs_rmdir+0x2d5/0x3c0 fs/namei.c:3873
 incfs_kill_sb+0xf7/0x200 fs/incfs/vfs.c:1973
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130
 task_work_run+0x127/0x190 kernel/task_work.c:189
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f90c6ef3097
Code: a2 c7 05 5c 26 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff413f4148 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f90c6ef3097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff413f4200
RBP: 00007fff413f4200 R08: 00007fff413f5200 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff413f5290
R13: 00007f90c6f872ca R14: 000000000001056c R15: 00007fff413f52d0
Modules linked in:
CR2: 0000000000000170
---[ end trace 5458fae90bc57b22 ]---
RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:165 [inline]
RIP: 0010:arch_atomic_inc_return include/linux/atomic-arch-fallback.h:286 [inline]
RIP: 0010:atomic_inc_return include/asm-generic/atomic-instrumented.h:251 [inline]
RIP: 0010:ihold+0x26/0x60 fs/inode.c:423
Code: 00 00 00 00 55 48 89 e5 41 56 53 48 89 fb e8 b1 7d b7 ff 48 8d bb 70 01 00 00 be 04 00 00 00 e8 a0 f5 f1 ff 41 be 01 00 00 00 <f0> 44 0f c1 b3 70 01 00 00 41 ff c6 bf 02 00 00 00 44 89 f6 e8 31
RSP: 0018:ffffc90000c07d38 EFLAGS: 00010246
RAX: ffff88811e68e200 RBX: 0000000000000000 RCX: ffff88811e68e2c0
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 00000000ffffffff
RBP: ffffc90000c07d48 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff0dcf648 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
FS:  0000555576f19500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000170 CR3: 0000000126811000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	a2 c7 05 5c 26 25 00 	movabs %al,0x25265c05c7
   7:	00 00
   9:	00 00                	add    %al,(%rax)
   b:	eb 96                	jmp    0xffffffa3
   d:	e8 e1 12 00 00       	call   0x12f3
  12:	90                   	nop
  13:	31 f6                	xor    %esi,%esi
  15:	e9 09 00 00 00       	jmp    0x23
  1a:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
  21:	00 00
  23:	b8 a6 00 00 00       	mov    $0xa6,%eax
  28:	0f 05                	syscall
* 2a:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax <-- trapping instruction
  30:	77 01                	ja     0x33
  32:	c3                   	ret
  33:	48 c7 c2 e8 ff ff ff 	mov    $0xffffffffffffffe8,%rdx
  3a:	f7 d8                	neg    %eax
  3c:	64 89 02             	mov    %eax,%fs:(%rdx)
  3f:	b8                   	.byte 0xb8

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/05 07:32 android13-5.10-lts 1bb06dbd8c78 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: null-ptr-deref Write in incfs_kill_sb
* Struck through repros no longer work on HEAD.