In the Linux kernel, the following vulnerability has been resolved: blk-mq: set RQF_USE_SCHED when the operation is known The cached requests are… (CVE-2026-98820)

The Linux kernel blk-mq subsystem had a vulnerability where cached requests were allocated for one operation but could be reused for another without correctly setting the RQF_USE_SCHED flag. Specifically, passthrough commands cleared this flag, so subsequent read/write bios would be inserted into the scheduler without proper preparation and freed without proper finishing. This caused the kyber scheduler to leak domain tokens acquired at dispatch and stall the queue. The patch changes the logic to set RQF_USE_SCHED only after the request is claimed by an operation, introducing a helper function blk_mq_rq_late_init() to handle this initialization, consolidating it with blk_mq_rq_time_init().

The vulnerability could cause resource leaks and queue stalls in the blk-mq subsystem of the Linux kernel, specifically affecting the kyber scheduler. This may degrade system performance or stability due to stalled I/O queues and leaked domain tokens. There is no indication of direct code execution or privilege escalation from the provided data.

A fix has been implemented in the Linux kernel to address this issue by properly setting the RQF_USE_SCHED flag after the request is claimed by an operation. Users should update to the fixed kernel versions once available. Since this is a kernel-level fix, applying the official kernel update is the recommended remediation.