[moderation] [fs?] KCSAN: data-race in generic_fillattr / touch_atime

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4f5e5092fdbf Merge tag 'net-6.8-rc5' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=139aee1c180000
kernel config: https://syzkaller.appspot.com/x/.config?x=b4c8befe72e5ccb8
dashboard link: https://syzkaller.appspot.com/bug?extid=9d0e6a86893402e94936
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/517fa88c8613/disk-4f5e5092.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cf7004696e01/vmlinux-4f5e5092.xz
kernel image: https://storage.googleapis.com/syzbot-assets/048b9047e0d5/bzImage-4f5e5092.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d0e6a...@syzkaller.appspotmail.com

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

write to 0xffff888104119860 of 8 bytes by task 3253 on cpu 1:
inode_set_atime_to_ts include/linux/fs.h:1541 [inline]
inode_update_timestamps fs/inode.c:1876 [inline]
generic_update_time fs/inode.c:1898 [inline]
inode_update_time fs/inode.c:1918 [inline]
touch_atime+0x1ed/0x340 fs/inode.c:1990
do_readlinkat+0x164/0x210 fs/stat.c:510
__do_sys_readlink fs/stat.c:532 [inline]
__se_sys_readlink fs/stat.c:529 [inline]
__x64_sys_readlink+0x47/0x50 fs/stat.c:529
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888104119860 of 8 bytes by task 3261 on cpu 0:
inode_get_atime include/linux/fs.h:1535 [inline]
generic_fillattr+0x16f/0x2f0 fs/stat.c:60
shmem_getattr+0x17b/0x200 mm/shmem.c:1139
vfs_getattr_nosec fs/stat.c:135 [inline]
vfs_getattr+0x198/0x1e0 fs/stat.c:176
vfs_statx+0x140/0x320 fs/stat.c:248
vfs_fstatat+0xcd/0x100 fs/stat.c:304
__do_sys_newfstatat fs/stat.c:468 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:462
__x64_sys_newfstatat+0x55/0x60 fs/stat.c:462
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000029d4ddc2 -> 0x000000002b9ea143

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3261 Comm: udevd Not tainted 6.8.0-rc4-syzkaller-00180-g4f5e5092fdbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop1, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0


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