[moderation] [kernfs?] KCSAN: data-race in kernfs_iop_permission / kernfs_iop_permission (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 80e54e84911a Linux 6.14-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14984654580000
kernel config: https://syzkaller.appspot.com/x/.config?x=958433697845b9a6
dashboard link: https://syzkaller.appspot.com/bug?extid=3838461eacfdddaf77ee
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/e94728c052e3/disk-80e54e84.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742f05e27746/vmlinux-80e54e84.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90d418e775f7/bzImage-80e54e84.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+383846...@syzkaller.appspotmail.com

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

write to 0xffff8881060deee4 of 4 bytes by task 3299 on cpu 1:
inode_set_mtime_to_ts include/linux/fs.h:1708 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x14c/0x210 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:525 [inline]
inode_permission+0x18c/0x300 fs/namei.c:592
may_create+0x18e/0x1f0 fs/namei.c:3175
vfs_mkdir+0x54/0x320 fs/namei.c:4298
do_mkdirat+0x136/0x2c0 fs/namei.c:4336
__do_sys_mkdirat fs/namei.c:4351 [inline]
__se_sys_mkdirat fs/namei.c:4349 [inline]
__x64_sys_mkdirat+0x4e/0x60 fs/namei.c:4349
x64_sys_call+0x1b6f/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:259
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881060deee4 of 4 bytes by task 3302 on cpu 0:
inode_set_mtime_to_ts include/linux/fs.h:1708 [inline]
set_inode_attr fs/kernfs/inode.c:163 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x14c/0x210 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:525 [inline]
inode_permission+0x18c/0x300 fs/namei.c:592
may_lookup fs/namei.c:1836 [inline]
link_path_walk+0x5c1/0x830 fs/namei.c:2427
path_openat+0x1af/0x1fc0 fs/namei.c:3985
do_filp_open+0x107/0x230 fs/namei.c:4016
do_sys_openat2+0xab/0x120 fs/open.c:1428
do_sys_open fs/open.c:1443 [inline]
__do_sys_openat fs/open.c:1459 [inline]
__se_sys_openat fs/open.c:1454 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1454
x64_sys_call+0x2b30/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0b587599 -> 0x0c08bfa3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3302 Comm: syz-executor Not tainted 6.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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[syzbot]

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