[moderation] [ext4?] KCSAN: data-race in _copy_to_iter / set_overhead (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8faabc041a00 Merge tag 'net-6.13-rc4' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1416afe8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=67aa69407438e9cf
dashboard link: https://syzkaller.appspot.com/bug?extid=5337104f1251590e4d0d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f5baa67fe4f0/disk-8faabc04.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bb458d3314fd/vmlinux-8faabc04.xz
kernel image: https://storage.googleapis.com/syzbot-assets/786aa68acfbb/bzImage-8faabc04.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+533710...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in _copy_to_iter / set_overhead

write to 0xffff88812d74b648 of 4 bytes by task 4122 on cpu 0:
set_overhead+0x28/0x40 fs/ext4/ioctl.c:1701
ext4_update_backup_sb fs/ext4/ioctl.c:152 [inline]
ext4_update_superblocks_fn+0x6af/0xc40 fs/ext4/ioctl.c:240
ext4_update_overhead+0xdc/0xf0 fs/ext4/ioctl.c:1714
ext4_fill_super+0x990/0x3a10 fs/ext4/super.c:5754
get_tree_bdev_flags+0x29f/0x310 fs/super.c:1636
get_tree_bdev+0x1f/0x30 fs/super.c:1659
ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5765
vfs_get_tree+0x56/0x1e0 fs/super.c:1814
do_new_mount+0x227/0x690 fs/namespace.c:3507
path_mount+0x49b/0xb30 fs/namespace.c:3834
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x27c/0x2d0 fs/namespace.c:4034
__x64_sys_mount+0x67/0x80 fs/namespace.c:4034
x64_sys_call+0x2c84/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:166
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

read to 0xffff88812d74b400 of 1024 bytes by task 3869 on cpu 1:
instrument_copy_to_user include/linux/instrumented.h:113 [inline]
copy_to_user_iter lib/iov_iter.c:24 [inline]
iterate_ubuf include/linux/iov_iter.h:30 [inline]
iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
iterate_and_advance include/linux/iov_iter.h:328 [inline]
_copy_to_iter+0x130/0xd00 lib/iov_iter.c:185
copy_page_to_iter+0x171/0x2b0 lib/iov_iter.c:362
copy_folio_to_iter include/linux/uio.h:189 [inline]
filemap_read+0x42d/0x6a0 mm/filemap.c:2697
blkdev_read_iter+0x20e/0x2c0 block/fops.c:770
new_sync_read fs/read_write.c:484 [inline]
vfs_read+0x5dc/0x700 fs/read_write.c:565
ksys_read+0xe8/0x1b0 fs/read_write.c:708
__do_sys_read fs/read_write.c:717 [inline]
__se_sys_read fs/read_write.c:715 [inline]
__x64_sys_read+0x42/0x50 fs/read_write.c:715
x64_sys_call+0x2874/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:1
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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3869 Comm: udevd Not tainted 6.13.0-rc3-syzkaller-00136-g8faabc041a00 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

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