------------[ cut here ]------------
WARNING: CPU: 0 PID: 313 at fs/inode.c:340 drop_nlink+0xce/0x110 fs/inode.c:340
Modules linked in:
CPU: 0 UID: 0 PID: 313 Comm: syz-executor413 Not tainted syzkaller #0 59fd58dbf897e2c8ba33f91efbb53ce34092dff9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:drop_nlink+0xce/0x110 fs/inode.c:340
Code: 04 00 00 be 08 00 00 00 e8 0f 0d ee ff f0 48 ff 83 b8 04 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 72 26 95 ff <0f> 0b eb 81 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 59 ff ff ff 4c
RSP: 0018:ffffc900011bfb48 EFLAGS: 00010293
RAX: ffffffff81f253fe RBX: ffff8881037ed6c0 RCX: ffff888121bab900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900011bfb70 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000237f58 R12: dffffc0000000000
R13: 1ffff110206fdae1 R14: ffff8881037ed708 R15: 0000000000000000
FS:  000055558da413c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558da527a8 CR3: 0000000126e50000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 shmem_rmdir+0x5f/0x90 mm/shmem.c:3826
 vfs_rmdir+0x3db/0x560 fs/namei.c:4348
 incfs_kill_sb+0x102/0x220 fs/incfs/vfs.c:1968
 deactivate_locked_super+0xd2/0x270 fs/super.c:478
 deactivate_super+0xb8/0xe0 fs/super.c:511
 cleanup_mnt+0x438/0x4d0 fs/namespace.c:1380
 __cleanup_mnt+0x1d/0x40 fs/namespace.c:1387
 task_work_run+0x1e5/0x260 kernel/task_work.c:246
 ptrace_notify+0x25a/0x290 kernel/signal.c:2427
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0x84/0x150 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare+0x21/0x40 kernel/entry/common.c:200
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x15/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fcd4fee1527
Code: bf 41 4d 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 64 85 09 00 00 00 00 00 eb 96 e8 b1 05 00 00 90 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe234a3858 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fcd4fee1527
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe234a3910
RBP: 00007ffe234a3910 R08: 00007ffe234a4910 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffe234a4980
R13: 000055558da42730 R14: 00007ffe234a4980 R15: 0000000000000001
 </TASK>
---[ end trace 0000000000000000 ]---
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: null-ptr-deref in atomic_inc_return include/linux/atomic/atomic-instrumented.h:453 [inline]
BUG: KASAN: null-ptr-deref in ihold+0x24/0x70 fs/inode.c:452
Write of size 4 at addr 0000000000000168 by task syz-executor413/313

CPU: 0 UID: 0 PID: 313 Comm: syz-executor413 Tainted: G        W          syzkaller #0 59fd58dbf897e2c8ba33f91efbb53ce34092dff9
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 print_report+0x3d/0x70 mm/kasan/report.c:484
 kasan_report+0x162/0x1a0 mm/kasan/report.c:594
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x25a/0x2b0 mm/kasan/generic.c:189
 __kasan_check_write+0x18/0x20 mm/kasan/shadow.c:37
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_inc_return include/linux/atomic/atomic-instrumented.h:453 [inline]
 ihold+0x24/0x70 fs/inode.c:452
 d_delete_notify include/linux/fsnotify.h:357 [inline]
 vfs_rmdir+0x25c/0x560 fs/namei.c:4361
 incfs_kill_sb+0x102/0x220 fs/incfs/vfs.c:1968
 deactivate_locked_super+0xd2/0x270 fs/super.c:478
 deactivate_super+0xb8/0xe0 fs/super.c:511
 cleanup_mnt+0x438/0x4d0 fs/namespace.c:1380
 __cleanup_mnt+0x1d/0x40 fs/namespace.c:1387
 task_work_run+0x1e5/0x260 kernel/task_work.c:246
 ptrace_notify+0x25a/0x290 kernel/signal.c:2427
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0x84/0x150 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare+0x21/0x40 kernel/entry/common.c:200
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x15/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fcd4fee1527
Code: bf 41 4d 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 64 85 09 00 00 00 00 00 eb 96 e8 b1 05 00 00 90 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe234a3858 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fcd4fee1527
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe234a3910
RBP: 00007ffe234a3910 R08: 00007ffe234a4910 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffe234a4980
R13: 000055558da42730 R14: 00007ffe234a4980 R15: 0000000000000001
 </TASK>
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000168
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0002 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 313 Comm: syz-executor413 Tainted: G    B   W          syzkaller #0 59fd58dbf897e2c8ba33f91efbb53ce34092dff9
Tainted: [B]=BAD_PAGE, [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:85 [inline]
RIP: 0010:raw_atomic_add_return include/linux/atomic/atomic-arch-fallback.h:564 [inline]
RIP: 0010:raw_atomic_inc_return include/linux/atomic/atomic-arch-fallback.h:1020 [inline]
RIP: 0010:atomic_inc_return include/linux/atomic/atomic-instrumented.h:454 [inline]
RIP: 0010:ihold+0x2a/0x70 fs/inode.c:452
Code: f3 0f 1e fa 55 48 89 e5 41 56 53 48 89 fb e8 5d 1d 95 ff 48 8d bb 68 01 00 00 be 04 00 00 00 e8 cc 03 ee ff 41 be 01 00 00 00 <f0> 44 0f c1 b3 68 01 00 00 41 ff c6 bf 02 00 00 00 44 89 f6 e8 6d
RSP: 0018:ffffc900011bfb88 EFLAGS: 00010246
RAX: ffff888121bab900 RBX: 0000000000000000 RCX: ffff888121bab900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900011bfb98 R08: ffffffff88bbb947 R09: 1ffffffff1177728
R10: dffffc0000000000 R11: fffffbfff1177729 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: dffffc0000000000
FS:  000055558da413c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000168 CR3: 0000000126e50000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 d_delete_notify include/linux/fsnotify.h:357 [inline]
 vfs_rmdir+0x25c/0x560 fs/namei.c:4361
 incfs_kill_sb+0x102/0x220 fs/incfs/vfs.c:1968
 deactivate_locked_super+0xd2/0x270 fs/super.c:478
 deactivate_super+0xb8/0xe0 fs/super.c:511
 cleanup_mnt+0x438/0x4d0 fs/namespace.c:1380
 __cleanup_mnt+0x1d/0x40 fs/namespace.c:1387
 task_work_run+0x1e5/0x260 kernel/task_work.c:246
 ptrace_notify+0x25a/0x290 kernel/signal.c:2427
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0x84/0x150 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare+0x21/0x40 kernel/entry/common.c:200
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x15/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fcd4fee1527
Code: bf 41 4d 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 64 85 09 00 00 00 00 00 eb 96 e8 b1 05 00 00 90 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe234a3858 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fcd4fee1527
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe234a3910
RBP: 00007ffe234a3910 R08: 00007ffe234a4910 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffe234a4980
R13: 000055558da42730 R14: 00007ffe234a4980 R15: 0000000000000001
 </TASK>
Modules linked in:
CR2: 0000000000000168
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_add_return arch/x86/include/asm/atomic.h:85 [inline]
RIP: 0010:raw_atomic_add_return include/linux/atomic/atomic-arch-fallback.h:564 [inline]
RIP: 0010:raw_atomic_inc_return include/linux/atomic/atomic-arch-fallback.h:1020 [inline]
RIP: 0010:atomic_inc_return include/linux/atomic/atomic-instrumented.h:454 [inline]
RIP: 0010:ihold+0x2a/0x70 fs/inode.c:452
Code: f3 0f 1e fa 55 48 89 e5 41 56 53 48 89 fb e8 5d 1d 95 ff 48 8d bb 68 01 00 00 be 04 00 00 00 e8 cc 03 ee ff 41 be 01 00 00 00 <f0> 44 0f c1 b3 68 01 00 00 41 ff c6 bf 02 00 00 00 44 89 f6 e8 6d
RSP: 0018:ffffc900011bfb88 EFLAGS: 00010246
RAX: ffff888121bab900 RBX: 0000000000000000 RCX: ffff888121bab900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900011bfb98 R08: ffffffff88bbb947 R09: 1ffffffff1177728
R10: dffffc0000000000 R11: fffffbfff1177729 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: dffffc0000000000
FS:  000055558da413c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000168 CR3: 0000000126e50000 CR4: 00000000003526b0
----------------
Code disassembly (best guess):
   0:	f3 0f 1e fa          	endbr64
   4:	55                   	push   %rbp
   5:	48 89 e5             	mov    %rsp,%rbp
   8:	41 56                	push   %r14
   a:	53                   	push   %rbx
   b:	48 89 fb             	mov    %rdi,%rbx
   e:	e8 5d 1d 95 ff       	call   0xff951d70
  13:	48 8d bb 68 01 00 00 	lea    0x168(%rbx),%rdi
  1a:	be 04 00 00 00       	mov    $0x4,%esi
  1f:	e8 cc 03 ee ff       	call   0xffee03f0
  24:	41 be 01 00 00 00    	mov    $0x1,%r14d
* 2a:	f0 44 0f c1 b3 68 01 	lock xadd %r14d,0x168(%rbx) <-- trapping instruction
  31:	00 00
  33:	41 ff c6             	inc    %r14d
  36:	bf 02 00 00 00       	mov    $0x2,%edi
  3b:	44 89 f6             	mov    %r14d,%esi
  3e:	e8                   	.byte 0xe8
  3f:	6d                   	insl   (%dx),%es:(%rdi)