CVE-2026-74392

Technical Description

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

dm: limit target bio polling to one shot

dm_poll_bio() is the ->poll_bio() callback for a stacked dm device.

The caller only knows about the dm queue, so it may decide to do a

spinning poll if it thinks a single queue is being polled. Passing those

flags unchanged to the mapped clone lets blk_mq_poll() spin on a target

queue from inside dm_poll_bio().

With io_uring IOPOLL on a dm-stripe target this can keep a task in

dm_poll_bio() -> bio_poll() -> blk_mq_poll()

long enough to trigger an RCU CPU stall, before io_uring gets back to

io_iopoll_check() and its need_resched() check.

Keep dm's ->poll_bio() bounded by forcing one-shot polling for target

bios. The caller can invoke dm_poll_bio() again if it wants to keep

polling, and it also gets a chance to reap completions or reschedule

between passes.

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