Linux Kernel Device Mapper dm_poll_bio resource consumption

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel. Affected by this vulnerability is the function dm_poll_bio of the component Device Mapper. Executing a manipulation can lead to resource consumption. This vulnerability is handled as CVE-2026-74392. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel (unknown version). It has been declared as critical. This vulnerability affects the function dm_poll_bio of the component Device Mapper. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-74392 since 08/15/2026. The exploitation appears to be easy. The attack can be initiated remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/15/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Applying the patch 6c4ede3b771adbb3bf21ad4e8b8f2f6f6120c4f7/5aa0f9231cbacade065cedd8e9b5ebd067231171 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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