[moderation] [fs?] WARNING in filename_linkat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e753c16cb3dd Merge tag 'spi-fix-v7.0-rc7' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16159b02580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d46eab0cfd31c214
dashboard link: https://syzkaller.appspot.com/bug?extid=86fbf0f061bbfa9d8171
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-e753c16c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fcae6ed94576/vmlinux-e753c16c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/af7d1624f62b/bzImage-e753c16c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+86fbf0...@syzkaller.appspotmail.com

syz.0.0: attempt to access beyond end of device
loop0: rw=8400896, sector=68719479080, nr_sectors = 8 limit=32768
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88803834c318, owner = 0x0, curr 0xffff88801ab68000, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.0/5346
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.0/5346
Modules linked in:
CPU: 0 UID: 0 PID: 5346 Comm: syz.0.0 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 a0 ec cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 00 ef 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 2a a1 0c 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000b28fd60 EFLAGS: 00010246
RAX: ffffffff8bccec80 RBX: ffff88803834c318 RCX: ffff88803834c318
RDX: 0000000000000000 RSI: ffffffff8bccef00 RDI: ffffffff90154c00
RBP: ffff88803834c370 R08: 0000000000000000 R09: ffff88801ab68000
R10: ffffffff8bccec80 R11: ffffed1007069865 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88803834c318 R15: 1ffff11007069864
FS: 00007f46a8ccf6c0(0000) GS:ffff88808ca49000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffffffff000 CR3: 000000001ec7f000 CR4: 0000000000352ef0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:1038 [inline]
end_dirop fs/namei.c:2953 [inline]
end_creating include/linux/namei.h:126 [inline]
end_creating_path fs/namei.c:4968 [inline]
filename_linkat+0x2d5/0x600 fs/namei.c:5823
__do_sys_link fs/namei.c:5853 [inline]
__se_sys_link+0x55/0x2c0 fs/namei.c:5849
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: 0033:0x7f46a7d9c819
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:00007f46a8ccefe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f46a8016180 RCX: 00007f46a7d9c819
RDX: 0000000000000000 RSI: 00002000000002c0 RDI: 00002000000001c0
RBP: 00007f46a7e32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f46a8016218 R14: 00007f46a8016180 R15: 00007ffc95af7668
</TASK>
----------------
Code disassembly (best guess):
0: cc int3
1: 8b 49 c7 mov -0x39(%rcx),%ecx
4: c2 a0 ec ret $0xeca0
7: cc int3
8: 8b 4c 0f 44 mov 0x44(%rdi,%rcx,1),%ecx
c: d0 48 8b rorb $1,-0x75(%rax)
f: 7c 24 jl 0x35
11: 08 48 c7 or %cl,-0x39(%rax)
14: c6 00 ef movb $0xef,(%rax)
17: cc int3
18: 8b 48 8b mov -0x75(%rax),%ecx
1b: 14 24 adc $0x24,%al
1d: 4c 89 f1 mov %r14,%rcx
20: 4d 89 e0 mov %r12,%r8
23: 4c 8b 4c 24 10 mov 0x10(%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 2a a1 0c 03 call 0x30ca162
38: e9 67 fd ff ff jmp 0xfffffda4
3d: 48 rex.W
3e: c7 .byte 0xc7
3f: c1 .byte 0xc1


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