CVE-2025-68823

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ublk: fix deadlock when reading partition table

When one process(such as udev) opens ublk block device (e.g., to read

the partition table via bdev_open()), a deadlock[1] can occur:

1. bdev_open() grabs disk->open_mutex

2. The process issues read I/O to ublk backend to read partition table

3. In __ublk_complete_rq(), blk_update_request() or blk_mq_end_request()

runs bio->bi_end_io() callbacks

4. If this triggers fput() on file descriptor of ublk block device, the

work may be deferred to current task's task work (see fput() implementation)

5. This eventually calls blkdev_release() from the same context

6. blkdev_release() tries to grab disk->open_mutex again

7. Deadlock: same task waiting for a mutex it already holds

The fix is to run blk_update_request() and blk_mq_end_request() with bottom

halves disabled. This forces blkdev_release() to run in kernel work-queue

context instead of current task work context, a

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References