[moderation] [fs?] KCSAN: data-race in generic_fillattr / setattr_copy (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 155a3c003e55 Merge tag 'for-6.16/dm-fixes-2' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b18382580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c8b73fe883c5b6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=db9be7fd1d56d4607cc0
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/b702b3a60562/disk-155a3c00.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/74f911fca904/vmlinux-155a3c00.xz
kernel image: https://storage.googleapis.com/syzbot-assets/36a9a45ae614/bzImage-155a3c00.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+db9be7...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in generic_fillattr / setattr_copy

write to 0xffff8881016ce6bc of 4 bytes by task 29290 on cpu 0:
inode_set_mtime_to_ts include/linux/fs.h:1718 [inline]
setattr_copy+0x2d3/0x4b0 fs/attr.c:361
shmem_setattr+0x566/0x840 mm/shmem.c:1343
notify_change+0x806/0x890 fs/attr.c:552
vfs_utimes+0x2fc/0x410 fs/utimes.c:66
do_utimes_path fs/utimes.c:99 [inline]
do_utimes+0x154/0x210 fs/utimes.c:140
__do_sys_utimensat fs/utimes.c:159 [inline]
__se_sys_utimensat fs/utimes.c:143 [inline]
__x64_sys_utimensat+0xc4/0x170 fs/utimes.c:143
x64_sys_call+0x1a2c/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:281
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881016ce6bc of 4 bytes by task 29291 on cpu 1:
inode_get_mtime_nsec include/linux/fs.h:1704 [inline]
inode_get_mtime include/linux/fs.h:1710 [inline]
generic_fillattr+0x20e/0x340 fs/stat.c:102
shmem_getattr+0x181/0x200 mm/shmem.c:1262
vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
vfs_getattr fs/stat.c:262 [inline]
vfs_statx_path fs/stat.c:299 [inline]
vfs_statx+0x113/0x390 fs/stat.c:356
vfs_fstatat+0x115/0x170 fs/stat.c:375
__do_sys_newfstatat fs/stat.c:542 [inline]
__se_sys_newfstatat+0x55/0x260 fs/stat.c:536
__x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
x64_sys_call+0x2c22/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:263
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x1804a085 -> 0x18466be8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29291 Comm: udevd Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.