[moderation] [block?] KCSAN: data-race in lo_ioctl / lo_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c8e97fc6b4c0 Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1397e571e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e9b421b7b0976d59
dashboard link: https://syzkaller.appspot.com/bug?extid=a54e507b9fa405371318
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/94e7e939ce47/disk-c8e97fc6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7432fadc8b3/vmlinux-c8e97fc6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/de8364e76ded/bzImage-c8e97fc6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a54e50...@syzkaller.appspotmail.com

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

read-write to 0xffff8881005f0104 of 1 bytes by task 2990 on cpu 1:
dev_set_uevent_suppress include/linux/device.h:938 [inline]
loop_change_fd drivers/block/loop.c:638 [inline]
lo_ioctl+0x124f/0x12e0 drivers/block/loop.c:1561
blkdev_ioctl+0x375/0x460 block/ioctl.c:633
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read-write to 0xffff8881005f0104 of 1 bytes by task 2987 on cpu 0:
dev_set_uevent_suppress include/linux/device.h:938 [inline]
loop_change_fd drivers/block/loop.c:638 [inline]
lo_ioctl+0x124f/0x12e0 drivers/block/loop.c:1561
blkdev_ioctl+0x375/0x460 block/ioctl.c:633
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x17 -> 0x07

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2987 Comm: syz-executor.1 Not tainted 6.7.0-rc5-syzkaller-00214-gc8e97fc6b4c0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================


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[syzbot]

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