[moderation] [fs?] KCSAN: data-race in generic_fillattr / setattr_copy (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d61f1cc5db79 Merge tag 'x86_cpu_for_6.19-rc1' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10b99512580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7ca02f11a9b5ae98
dashboard link: https://syzkaller.appspot.com/bug?extid=f2da64f8adbed4803930
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/21bb911c887b/disk-d61f1cc5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e3c2031cd2c9/vmlinux-d61f1cc5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b160f4313baa/bzImage-d61f1cc5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2da64...@syzkaller.appspotmail.com

udevd[3621]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
==================================================================
BUG: KCSAN: data-race in generic_fillattr / setattr_copy

write to 0xffff8881022b4c90 of 4 bytes by task 3311 on cpu 1:
inode_set_atime_to_ts include/linux/fs.h:1624 [inline]
setattr_copy+0x25b/0x4a0 fs/attr.c:351
shmem_setattr+0x566/0x840 mm/shmem.c:1337
notify_change+0x872/0x8f0 fs/attr.c:546
vfs_utimes+0x2fc/0x410 fs/utimes.c:66
do_utimes_path fs/utimes.c:100 [inline]
do_utimes+0x154/0x210 fs/utimes.c:141
__do_sys_utimensat fs/utimes.c:160 [inline]
__se_sys_utimensat fs/utimes.c:144 [inline]
__x64_sys_utimensat+0xc4/0x170 fs/utimes.c:144
x64_sys_call+0x278c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:281
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881022b4c90 of 4 bytes by task 3621 on cpu 0:
inode_get_atime_nsec include/linux/fs.h:1609 [inline]
inode_get_atime include/linux/fs.h:1615 [inline]
generic_fillattr+0x172/0x340 fs/stat.c:96
shmem_getattr+0x181/0x200 mm/shmem.c:1256
vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
vfs_getattr fs/stat.c:262 [inline]
vfs_fstat fs/stat.c:281 [inline]
__do_sys_newfstat fs/stat.c:555 [inline]
__se_sys_newfstat+0x96/0x2e0 fs/stat.c:550
__x64_sys_newfstat+0x31/0x40 fs/stat.c:550
x64_sys_call+0x2c51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:6
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x2a04bf5c -> 0x3263a75f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3621 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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