CVE-2026-74392 in Linux
Summary
by MITRE • 08/15/2026
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.
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