[moderation] [fs?] KCSAN: data-race in dentry_unlink_inode / path_openat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 516471569089 Merge tag 'libcrypto-fixes-for-linus' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=168b577c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b319ff1b6a2797ca
dashboard link: https://syzkaller.appspot.com/bug?extid=f8e6c6d437af7e678fd0
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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: https://storage.googleapis.com/syzbot-assets/daca6d82d1e1/disk-51647156.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3e0d93470f33/vmlinux-51647156.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27efb1907b03/bzImage-51647156.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8e6c6...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in dentry_unlink_inode / path_openat

write to 0xffff88811b1944b0 of 8 bytes by task 3530 on cpu 0:
__d_clear_type_and_inode fs/dcache.c:420 [inline]
dentry_unlink_inode+0x65/0x260 fs/dcache.c:457
__dentry_kill+0x18d/0x4b0 fs/dcache.c:670
finish_dput+0x2b/0x200 fs/dcache.c:879
dput+0x52/0x60 fs/dcache.c:928
end_renaming fs/namei.c:4052 [inline]
do_renameat2+0x44a/0x810 fs/namei.c:6049
__do_sys_rename fs/namei.c:6090 [inline]
__se_sys_rename fs/namei.c:6088 [inline]
__x64_sys_rename+0x58/0x70 fs/namei.c:6088
x64_sys_call+0x24e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b1944b0 of 8 bytes by task 3008 on cpu 1:
step_into fs/namei.c:2080 [inline]
open_last_lookups fs/namei.c:4575 [inline]
path_openat+0x677/0x23b0 fs/namei.c:4784
do_filp_open+0x109/0x230 fs/namei.c:4814
do_sys_openat2+0xa6/0x150 fs/open.c:1430
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1447
x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88812162f7b8 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3008 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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