[moderation] [exfat?] KCSAN: data-race in _copy_to_iter / fat_set_state (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ad1b832bf1cf Merge tag 'devicetree-fixes-for-6.14-1' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10458898580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c8889d5a0d6060f3
dashboard link: https://syzkaller.appspot.com/bug?extid=f2b943aec596ea162a82
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [hiro...@mail.parknet.co.jp linki...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org sj155...@samsung.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/97569278b52d/disk-ad1b832b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/92ff2900c3e3/vmlinux-ad1b832b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3ece26955a52/bzImage-ad1b832b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f2b943...@syzkaller.appspotmail.com

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

write to 0xffff88813269a041 of 1 bytes by task 6098 on cpu 0:
fat_set_state+0x16e/0x1e0
fat_fill_super+0x17c6/0x1c30 fs/fat/inode.c:1832
vfat_fill_super+0x24/0x30 fs/fat/namei_vfat.c:1197
get_tree_bdev_flags+0x29f/0x310 fs/super.c:1636
get_tree_bdev+0x1f/0x30 fs/super.c:1659
vfat_get_tree+0x1c/0x30 fs/fat/namei_vfat.c:1202
vfs_get_tree+0x56/0x1e0 fs/super.c:1814
do_new_mount+0x227/0x690 fs/namespace.c:3560
path_mount+0x49b/0xb30 fs/namespace.c:3887
do_mount fs/namespace.c:3900 [inline]
__do_sys_mount fs/namespace.c:4111 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:4088
__x64_sys_mount+0x67/0x80 fs/namespace.c:4088
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 0xffff88813269a000 of 1024 bytes by task 4012 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:198 [inline]
filemap_read+0x43d/0x8c0 mm/filemap.c:2742
blkdev_read_iter+0x228/0x2d0 block/fops.c:796
new_sync_read fs/read_write.c:484 [inline]
vfs_read+0x5cc/0x6f0 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: 4012 Comm: udevd Not tainted 6.14.0-rc2-syzkaller-00303-gad1b832bf1cf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================


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[syzbot]

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