CVE-2026-74392: dm: limit target bio polling to one shot

Published Aug 15, 2026
·
Updated

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

dm: limit target bio polling to one shot

dmpollbio() is the ->pollbio() 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 blkmqpoll() spin on a target queue from inside dmpollbio().

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

dmpollbio() -> biopoll() -> blkmqpoll()

long enough to trigger an RCU CPU stall, before iouring gets back to ioiopollcheck() and its needresched() check.

Keep dm's ->pollbio() bounded by forcing one-shot polling for target bios. The caller can invoke dmpollbio() again if it wants to keep polling, and it also gets a chance to reap completions or reschedule between passes.

Event History

Aug 15, 2026
CVE Published
via MITRE·05:59 AM
Data Sourced
via MITRE·05:59 AM
Description
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CVE-2026-74392 - dm: limit target bio polling to one shot - SecAlerts