[moderation] [fs?] KCSAN: data-race in drop_nlink / generic_fillattr (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 87adedeba51a Merge tag 'net-6.8-rc7' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17450b74180000
kernel config: https://syzkaller.appspot.com/x/.config?x=53006d590acdf777
dashboard link: https://syzkaller.appspot.com/bug?extid=36c620456f1103f87b6a
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/85879d80665b/disk-87adedeb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/594eb01e8ed8/vmlinux-87adedeb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c4cbd4a49e35/bzImage-87adedeb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+36c620...@syzkaller.appspotmail.com

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

write to 0xffff8881384ef898 of 4 bytes by task 7858 on cpu 1:
drop_nlink+0x3b/0x90 fs/inode.c:332
shmem_unlink+0x169/0x180 mm/shmem.c:3370
shmem_rename2+0x1dc/0x2c0 mm/shmem.c:3449
vfs_rename+0x867/0x9c0 fs/namei.c:4883
do_renameat2+0x732/0xa60 fs/namei.c:5040
__do_sys_rename fs/namei.c:5087 [inline]
__se_sys_rename fs/namei.c:5085 [inline]
__x64_sys_rename+0x5c/0x70 fs/namei.c:5085
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 0xffff8881384ef898 of 4 bytes by task 3169 on cpu 0:
generic_fillattr+0xf8/0x2f0 fs/stat.c:55
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: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3169 Comm: udevd Not tainted 6.8.0-rc6-syzkaller-00120-g87adedeba51a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
I/O error, dev loop0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
I/O error, dev loop0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0


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[syzbot]

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