High [CVE-2026-64152] Handle unmap error when iommu_debug is enabled
This high-severity Red Hat Linux advisory covers CVE-2026-64152 affecting Red Hat Enterprise Linux 10, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: iommu: Handle unmap error when iommu_debug is enabled Sashiko noticed a latent bug where the map error flow called iommu_unmap() which calls iommu_debug_unmap_begin()/iommu_debug_unmap_end() however since this is an error path the map flow never actually established the original iommu_debug_map() it will malfunction.
Lift the unmap error handling into iommu_map_nosync() and reorder it so the trace_map()/iommu_debug_map() records the partial mapping and then immediately unmaps it. This avoid creating the unbalanced tracking and provides saner tracing instead of a unmap unmatched to any map.
A flaw was found in the Linux kernel's Input/Output Memory Management Unit (IOMMU) subsystem when `iommu_debug` is enabled. This issue occurs because an error handling path attempts to unmap memory without a proper initial mapping, leading to an inconsistent state within the IOMMU's debugging and tracing mechanisms.
This malfunction could result in unbalanced tracking, potentially affecting system stability or the accuracy of IOMMU debugging information. Red Hat severity: Moderate — CVSS 7.1 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H).
Weakness: CWE-832. Affected Red Hat products: Red Hat Enterprise Linux 10.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Mitigation checklist
- To mitigate this issue in Red Hat In-Vehicle OS, ensure that the `iommu_debug` kernel parameter is not enabled. This can typically be achieved by verifying that `iommu_debug` is not present in the kernel command line arguments during boot. Disabling this debug feature may impact diagnostic capabilities but will prevent the vulnerable code path from being exercised. A system reboot is required for changes to kernel boot parameters to take effect.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
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