UBUNTU-CVE-2026-74392: Medium severity ubuntu/linux-hwe-edge vulnerability
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 7.0.0-1025.26 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 7.0.0-1023.23 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
Force dm target bio polling to one shot by passing one-shot polling flags to mapped clone bios, allowing the caller to invoke dm_poll_bio() again between polling passes.
Event History
Frequently Asked Questions
Which workloads are most likely to encounter this issue?
The described trigger involves io_uring IOPOLL used with a device-mapper striped target (dm-stripe). Systems not using that combination are not identified as affected by the provided details.
What does an attacker or triggering workload need to do?
A workload needs to cause polling through a stacked device-mapper device such that dm_poll_bio() passes spinning poll flags to a mapped target queue. With io_uring IOPOLL on dm-stripe, this can keep a task polling long enough to trigger an RCU CPU stall.
What is the operational impact?
The affected task can remain in the device-mapper and block polling path for an extended period, potentially causing an RCU CPU stall. The fix bounds device-mapper target polling to a single pass so the caller can process completions or reschedule before polling again.