CVE-2026-74392: dm: limit target bio polling to one shot
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.
- Upgrade
Upgrade
ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
Upgrade
ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
Upgrade
ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
Upgrade
ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
Upgrade
ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
Upgrade
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
Upgrade
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
Upgrade
ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
Upgrade
ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74392?
CVE-2026-74392 has a risk rating of 23, indicating a significant vulnerability in the Linux kernel.
How do I fix CVE-2026-74392?
To fix CVE-2026-74392, you should update your Linux kernel to the latest stable version where this vulnerability has been patched.
What systems are affected by CVE-2026-74392?
CVE-2026-74392 affects systems using the Linux kernel with components that utilize the dm_poll_bio() callback.
What are the implications of CVE-2026-74392?
The implications of CVE-2026-74392 may include performance degradation and potential denial of service due to inefficient polling mechanisms.
How can I mitigate the risks associated with CVE-2026-74392?
To mitigate the risks associated with CVE-2026-74392, ensure that your Linux kernel is regularly updated and monitor affected systems for unusual behavior.