syzbot
WARNING in lookup_slow (4)
Status:
moderation: reported on 2025/05/26 09:57
Subsystems:
fs
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+2b8d9d5c6bae92cffb1d@syzkaller.appspotmail.com
First crash: 450d, last: 18h13m
Sample crash report:
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem)): count = 0x0, magic = 0xffff888052452d18, owner = 0x0, curr 0xffff88802820dd00, list not empty
WARNING: kernel/locking/rwsem.c:1384 at __up_read+0x6a5/0x930 kernel/locking/rwsem.c:1384, CPU#1: syz.6.849/9074
Modules linked in:
CPU: 1 UID: 0 PID: 9074 Comm: syz.6.849 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__up_read+0x77d/0x930 kernel/locking/rwsem.c:1384
Code: 8b 49 c7 c2 40 03 ed 8b 4c 0f 44 d0 48 8b 7c 24 28 48 c7 c6 00 03 ed 8b 48 8b 54 24 18 4c 89 e9 4d 89 e0 4c 8b 4c 24 08 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 c5 a5 2d 03 4c 8b 3c 24 48 8b 5c 24
RSP: 0018:ffffc90010a27858 EFLAGS: 00010246
RAX: ffffffff8bed0360 RBX: 1ffff1100a48a5a4 RCX: ffff888052452d18
RDX: 0000000000000000 RSI: ffffffff8bed0300 RDI: ffffffff905b17f0
RBP: ffffc90010a27930 R08: 0000000000000000 R09: ffff88802820dd00
R10: ffffffff8bed0360 R11: ffffed100a48a5a5 R12: 0000000000000000
R13: ffff888052452d18 R14: ffff888052452d70 R15: ffff888052452d20
FS: 00007fecd34326c0(0000) GS:ffff888125049000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f39fad48000 CR3: 00000000775cd000 CR4: 0000000000350ef0
Call Trace:
<TASK>
inode_unlock_shared include/linux/fs.h:1049 [inline]
lookup_slow+0x5e/0x70 fs/namei.c:1937
walk_component fs/namei.c:2282 [inline]
link_path_walk+0xd2a/0x1910 fs/namei.c:2656
path_openat+0x236/0x3830 fs/namei.c:4859
do_file_open+0x23e/0x4a0 fs/namei.c:4892
do_sys_openat2+0x115/0x200 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fecd259e0d9
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:00007fecd3432028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fecd2826090 RCX: 00007fecd259e0d9
RDX: 0000000000000002 RSI: 0000200000000300 RDI: ffffffffffffff9c
RBP: 00007fecd2635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecd2826128 R14: 00007fecd2826090 R15: 00007fff5ceeff98
</TASK>
----------------
Code disassembly (best guess):
0: 8b 49 c7 mov -0x39(%rcx),%ecx
3: c2 40 03 ret $0x340
6: ed in (%dx),%eax
7: 8b 4c 0f 44 mov 0x44(%rdi,%rcx,1),%ecx
b: d0 48 8b rorb $1,-0x75(%rax)
e: 7c 24 jl 0x34
10: 28 48 c7 sub %cl,-0x39(%rax)
13: c6 00 03 movb $0x3,(%rax)
16: ed in (%dx),%eax
17: 8b 48 8b mov -0x75(%rax),%ecx
1a: 54 push %rsp
1b: 24 18 and $0x18,%al
1d: 4c 89 e9 mov %r13,%rcx
20: 4d 89 e0 mov %r12,%r8
23: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9
28: 41 52 push %r10
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 83 c4 08 add $0x8,%rsp
33: e8 c5 a5 2d 03 call 0x32da5fd
38: 4c 8b 3c 24 mov (%rsp),%r15
3c: 48 rex.W
3d: 8b .byte 0x8b
3e: 5c pop %rsp
3f: 24 .byte 0x24
* Struck through repros no longer work on HEAD.