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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d1d36025a617 Merge tag 'probes-v6.19' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1272fcc2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fe265072cbd2f67a
dashboard link: https://syzkaller.appspot.com/bug?extid=f6f46f4f4282fb9ec53f
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/a49a20ff0279/disk-d1d36025.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82299341ac86/vmlinux-d1d36025.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c7a8896df36f/bzImage-d1d36025.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f6f46f...@syzkaller.appspotmail.com

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

write to 0xffff888104957830 of 4 bytes by task 3767 on cpu 1:
inode_set_ctime_to_ts+0x84/0x170 fs/inode.c:2744
inode_set_ctime_current+0x1cd/0x760 fs/inode.c:2807
shmem_symlink+0x36b/0x3d0 mm/shmem.c:4133
vfs_symlink+0x1b4/0x1f0 fs/namei.c:5514
do_symlinkat+0xf0/0x470 fs/namei.c:5541
__do_sys_symlink fs/namei.c:5567 [inline]
__se_sys_symlink fs/namei.c:5565 [inline]
__x64_sys_symlink+0x50/0x60 fs/namei.c:5565
x64_sys_call+0x24a9/0x3000 arch/x86/include/generated/asm/syscalls_64.h:89
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 0xffff888104957830 of 4 bytes by task 3409 on cpu 0:
inode_get_ctime_nsec include/linux/fs.h:1688 [inline]
inode_get_ctime include/linux/fs.h:1694 [inline]
generic_fillattr+0x1d1/0x340 fs/stat.c:101
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_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+0x111f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
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: 0x34360929 -> 0x3b75c6f7

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3409 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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