Re: [syzbot] [exfat?] [gfs2?] WARNING in filename_symlinkat

syzbot
2026-03-06T06:04:02Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in filename_symlinkat

------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88801248a898, owner = 0x0, curr 0xffff8880008924c0, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.108/6598
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.108/6598
Modules linked in:
CPU: 0 UID: 0 PID: 6598 Comm: syz.0.108 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__up_write kernel/locking/rwsem.c:1380 [inline]
RIP: 0010:up_write+0x388/0x410 kernel/locking/rwsem.c:1643
Code: cc 8b 49 c7 c2 80 eb cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 e0 ed cc 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 10 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 da a6 0b 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000c06fd80 EFLAGS: 00010246
RAX: ffffffff8bcceb60 RBX: ffff88801248a898 RCX: ffff88801248a898
RDX: 0000000000000000 RSI: ffffffff8bccede0 RDI: ffffffff901506e0
RBP: ffff88801248a8f0 R08: 0000000000000000 R09: ffff8880008924c0
R10: ffffffff8bcceb60 R11: ffffed1002491515 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88801248a898 R15: 1ffff11002491514
FS: 00007f7a71dfe6c0(0000) GS:ffff88808ca56000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000040e68000 CR4: 0000000000352ef0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:1038 [inline]
end_creating_path fs/namei.c:4970 [inline]
filename_symlinkat+0x314/0x570 fs/namei.c:5656
__do_sys_symlinkat fs/namei.c:5674 [inline]
__se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5669
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7a7279c799
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:00007f7a71dfe028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007f7a72a16090 RCX: 00007f7a7279c799
RDX: 00002000000003c0 RSI: 0000000000000007 RDI: 0000200000000240
RBP: 00007f7a72832bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7a72a16128 R14: 00007f7a72a16090 R15: 00007ffd323678c8
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 49 c7 c2 80 eb cc 8b mov $0xffffffff8bcceb80,%r10
7: 4c 0f 44 d0 cmove %rax,%r10
b: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi
10: 48 c7 c6 e0 ed cc 8b mov $0xffffffff8bccede0,%rsi
17: 48 8b 14 24 mov (%rsp),%rdx
1b: 4c 89 f1 mov %r14,%rcx
1e: 4d 89 e0 mov %r12,%r8
21: 4c 8b 4c 24 10 mov 0x10(%rsp),%r9
26: 41 52 push %r10
* 28: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2d: 48 83 c4 08 add $0x8,%rsp
31: e8 da a6 0b 03 call 0x30ba710
36: e9 67 fd ff ff jmp 0xfffffda2
3b: 48 rex.W
3c: c7 .byte 0xc7
3d: c1 .byte 0xc1

Tested on:

commit: 5ee8dbf5 Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1602f006580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5c49ee0942d1cdb
dashboard link: https://syzkaller.appspot.com/bug?extid=2ed46b6b748df855347f
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=1666ab5a580000