[moderation] [kernfs?] KCSAN: data-race in kernfs_iop_permission / kernfs_iop_permission (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4c06e63b9203 Merge tag 'for-6.16-rc4-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10218f70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=eea96b85b0259840
dashboard link: https://syzkaller.appspot.com/bug?extid=013f2a991e66cd449c82
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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/a29ad39ab029/disk-4c06e63b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccd884b8dad2/vmlinux-4c06e63b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/96b61fc8e436/bzImage-4c06e63b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+013f2a...@syzkaller.appspotmail.com

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

write to 0xffff888106de5884 of 4 bytes by task 3314 on cpu 1:
inode_set_mtime_to_ts include/linux/fs.h:1718 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x163/0x220 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:526 [inline]
inode_permission+0x1ca/0x310 fs/namei.c:593
may_lookup fs/namei.c:1860 [inline]
link_path_walk+0x63c/0x900 fs/namei.c:2454
path_openat+0x1de/0x2170 fs/namei.c:4051
do_filp_open+0x109/0x230 fs/namei.c:4082
do_sys_openat2+0xa6/0x110 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1463
x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
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

write to 0xffff888106de5884 of 4 bytes by task 3310 on cpu 0:
inode_set_mtime_to_ts include/linux/fs.h:1718 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x163/0x220 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:526 [inline]
inode_permission+0x1ca/0x310 fs/namei.c:593
may_create+0x196/0x1f0 fs/namei.c:3239
vfs_mkdir+0x5a/0x340 fs/namei.c:4358
do_mkdirat+0x132/0x3f0 fs/namei.c:4408
__do_sys_mkdirat fs/namei.c:4425 [inline]
__se_sys_mkdirat fs/namei.c:4423 [inline]
__x64_sys_mkdirat+0x4c/0x60 fs/namei.c:4423
x64_sys_call+0x2be0/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:259
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: 0x3a48e9b7 -> 0x00f993fc

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3310 Comm: syz-executor Not tainted 6.16.0-rc4-syzkaller-00123-g4c06e63b9203 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

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