syzbot

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 0 UID: 0 PID: 384 Comm: syz.2.17 Not tainted syzkaller #0 bfede744b46277b76d69ebe6cb8c22209d769bcb
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:d_really_is_positive include/linux/dcache.h:514 [inline]
RIP: 0010:fuse_atomic_open+0x1b6/0x440 fs/fuse/dir.c:962
Code: 8b 6d bc 44 89 ee 83 e6 40 31 ff e8 a4 60 48 ff 44 89 e8 83 e0 40 75 07 e8 57 5c 48 ff eb 25 4d 8d 6e 30 4c 89 e8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ef e8 5c 20 a0 ff 49 83 7d 00 00 74 26 e8
RSP: 0018:ffffc90000e8f950 EFLAGS: 00010206
RAX: 0000000000000009 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff8881155ecc00 RSI: 0000000000000040 RDI: 0000000000000000
RBP: ffffc90000e8f9b0 R08: 0000000000000004 R09: 0000000000000004
R10: fffff520001d1e9c R11: 0000000000000000 R12: ffff888128878000
R13: 000000000000004b R14: 000000000000001b R15: ffff88812a639680
FS:  00007f7904cdb6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000005fe0 CR3: 00000001153ea000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 atomic_open fs/namei.c:3463 [inline]
 lookup_open fs/namei.c:3574 [inline]
 open_last_lookups fs/namei.c:3702 [inline]
 path_openat+0x116f/0x34f0 fs/namei.c:3938
 do_filp_open+0x1f5/0x440 fs/namei.c:3968
 do_sys_openat2+0x134/0x1d0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0x13a/0x170 fs/open.c:1466
 x64_sys_call+0xe69/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f7903d9acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7904cdb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7904015fa0 RCX: 00007f7903d9acb9
RDX: 0000000000000040 RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f7903e08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000020 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7904016038 R14: 00007f7904015fa0 R15: 00007ffcc04ddb78
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:d_really_is_positive include/linux/dcache.h:514 [inline]
RIP: 0010:fuse_atomic_open+0x1b6/0x440 fs/fuse/dir.c:962
Code: 8b 6d bc 44 89 ee 83 e6 40 31 ff e8 a4 60 48 ff 44 89 e8 83 e0 40 75 07 e8 57 5c 48 ff eb 25 4d 8d 6e 30 4c 89 e8 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 ef e8 5c 20 a0 ff 49 83 7d 00 00 74 26 e8
RSP: 0018:ffffc90000e8f950 EFLAGS: 00010206
RAX: 0000000000000009 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff8881155ecc00 RSI: 0000000000000040 RDI: 0000000000000000
RBP: ffffc90000e8f9b0 R08: 0000000000000004 R09: 0000000000000004
R10: fffff520001d1e9c R11: 0000000000000000 R12: ffff888128878000
R13: 000000000000004b R14: 000000000000001b R15: ffff88812a639680
FS:  00007f7904cdb6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000005fe0 CR3: 00000001153ea000 CR4: 00000000003526b0
----------------
Code disassembly (best guess):
   0:	8b 6d bc             	mov    -0x44(%rbp),%ebp
   3:	44 89 ee             	mov    %r13d,%esi
   6:	83 e6 40             	and    $0x40,%esi
   9:	31 ff                	xor    %edi,%edi
   b:	e8 a4 60 48 ff       	call   0xff4860b4
  10:	44 89 e8             	mov    %r13d,%eax
  13:	83 e0 40             	and    $0x40,%eax
  16:	75 07                	jne    0x1f
  18:	e8 57 5c 48 ff       	call   0xff485c74
  1d:	eb 25                	jmp    0x44
  1f:	4d 8d 6e 30          	lea    0x30(%r14),%r13
  23:	4c 89 e8             	mov    %r13,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 ef             	mov    %r13,%rdi
  33:	e8 5c 20 a0 ff       	call   0xffa02094
  38:	49 83 7d 00 00       	cmpq   $0x0,0x0(%r13)
  3d:	74 26                	je     0x65
  3f:	e8                   	.byte 0xe8