[moderation] [kernfs?] KCSAN: data-race in kernfs_iop_permission / kernfs_iop_permission (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: adc218676eef Linux 6.12
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145b0930580000
kernel config: https://syzkaller.appspot.com/x/.config?x=44f4147e19698730
dashboard link: https://syzkaller.appspot.com/bug?extid=4c0fe01a63464cb27a6b
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/b6d08a612eec/disk-adc21867.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/da5aa2b2fdff/vmlinux-adc21867.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cb8237608646/bzImage-adc21867.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c0fe0...@syzkaller.appspotmail.com

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

write to 0xffff8881064ccc80 of 4 bytes by task 3321 on cpu 1:
inode_set_ctime_to_ts include/linux/fs.h:1678 [inline]
set_inode_attr fs/kernfs/inode.c:164 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x17f/0x220 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:468 [inline]
inode_permission+0x18c/0x300 fs/namei.c:535
may_lookup fs/namei.c:1775 [inline]
link_path_walk+0x5f3/0x820 fs/namei.c:2366
path_openat+0x1af/0x1fa0 fs/namei.c:3929
do_filp_open+0xf7/0x200 fs/namei.c:3960
do_sys_openat2+0xab/0x120 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_openat fs/open.c:1446 [inline]
__se_sys_openat fs/open.c:1441 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1441
x64_sys_call+0x1025/0x2d60 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

write to 0xffff8881064ccc80 of 4 bytes by task 3322 on cpu 0:
inode_set_ctime_to_ts include/linux/fs.h:1678 [inline]
set_inode_attr fs/kernfs/inode.c:164 [inline]
kernfs_refresh_inode fs/kernfs/inode.c:177 [inline]
kernfs_iop_permission+0x17f/0x220 fs/kernfs/inode.c:288
do_inode_permission fs/namei.c:468 [inline]
inode_permission+0x18c/0x300 fs/namei.c:535
may_lookup fs/namei.c:1775 [inline]
link_path_walk+0x5f3/0x820 fs/namei.c:2366
path_parentat fs/namei.c:2627 [inline]
__filename_parentat+0x13c/0x3c0 fs/namei.c:2651
filename_parentat fs/namei.c:2669 [inline]
filename_create+0x77/0x2b0 fs/namei.c:4007
do_mkdirat+0x63/0x2a0 fs/namei.c:4272
__do_sys_mkdirat fs/namei.c:4295 [inline]
__se_sys_mkdirat fs/namei.c:4293 [inline]
__x64_sys_mkdirat+0x4e/0x60 fs/namei.c:4293
x64_sys_call+0x2cd3/0x2d60 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

value changed: 0x191bdce5 -> 0x01c5d6b3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3322 Comm: syz-executor Not tainted 6.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
==================================================================


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[syzbot]

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