[moderation] [kernfs?] KCSAN: data-race in kernfs_iop_getattr / kernfs_iop_permission

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 755bc1335e3b Merge tag 'riscv-for-linus-6.19-rc5' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11563922580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c160236e1ef1e401
dashboard link: https://syzkaller.appspot.com/bug?extid=d00c45ee11ee2214b468
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [gre...@linuxfoundation.org linux-...@vger.kernel.org t...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3c2157ef5c58/disk-755bc133.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6e7ee2fc68bf/vmlinux-755bc133.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8567d8f85a73/bzImage-755bc133.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d00c45...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in kernfs_iop_getattr / kernfs_iop_permission

write to 0xffff888100428c78 of 4 bytes by task 13723 on cpu 0:
inode_set_atime_to_ts include/linux/fs.h:1624 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:179 [inline]
kernfs_iop_getattr+0x12f/0x220 fs/kernfs/inode.c:194
vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
vfs_getattr fs/stat.c:262 [inline]
vfs_fstat fs/stat.c:281 [inline]
vfs_fstatat+0xd8/0x170 fs/stat.c:373
__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+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888100428c78 of 4 bytes by task 12274 on cpu 1:
inode_set_atime_to_ts include/linux/fs.h:1624 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:179 [inline]
kernfs_iop_permission+0x12b/0x220 fs/kernfs/inode.c:290
do_inode_permission fs/namei.c:526 [inline]
inode_permission+0x2de/0x3c0 fs/namei.c:596
lookup_inode_permission_may_exec fs/namei.c:636 [inline]
may_lookup fs/namei.c:1923 [inline]
link_path_walk+0xaf6/0xe30 fs/namei.c:2545
path_parentat fs/namei.c:2801 [inline]
__filename_parentat+0x15c/0x3f0 fs/namei.c:2825
filename_parentat fs/namei.c:2843 [inline]
do_unlinkat+0x94/0x4b0 fs/namei.c:5417
__do_sys_unlink fs/namei.c:5483 [inline]
__se_sys_unlink fs/namei.c:5481 [inline]
__x64_sys_unlink+0x2e/0x40 fs/namei.c:5481
x64_sys_call+0x2f48/0x3000 arch/x86/include/generated/asm/syscalls_64.h:88
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x1899495d -> 0x2354621a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12274 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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