CVE-2025-68756

A deadlock vulnerability was found in the Linux kernel's block layer when using shared tag sets with NVMe devices. The blk_mq_quiesce_tagset() and blk_mq_update_tag_set_shared() functions both acquire set->tag_list_lock, leading to circular lock dependency. When an NVMe command times out while another thread is removing a namespace, both threads wait indefinitely for each other, causing a complete system hang.

This deadlock requires specific timing conditions involving NVMe device timeout and namespace removal operations occurring simultaneously. Affected systems will hang and require a hard reboot to recover. The vulnerability primarily affects systems with multiple NVMe namespaces sharing a tag set under heavy I/O load with device errors.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.