CVE-2025-40058: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40058 is a vulnerability discovered in the Linux kernel related to IOMMU/VT-d dirty tracking functionality. The issue was disclosed on October 28, 2025, affecting the Linux kernel's input/output memory management unit (IOMMU) implementation (NVD).

The vulnerability involves the IOMMU's dirty page tracking mechanism, which relies on atomic updates to dirty bits in paging-structure entries. The issue occurs when the paging-structure memory lacks coherency between the IOMMU and CPU. According to the Intel VT-d specification Section 3.10 'Snoop Behavior', attempting atomic updates to A/EA/D bits in non-snooped paging-structure entries results in a non-recoverable fault (NVD).

When the IOMMU operates in an incoherent mode while dirty page tracking is enabled, it can lead to non-recoverable faults in the system, potentially affecting system stability and functionality (NVD).

The vulnerability has been addressed by implementing a fix that marks SSADS as supported only when both ecap_slads and ecap_smpwc are supported. This prevents the IOMMU from being incorrectly configured for dirty page tracking when operating in an incoherent mode (NVD).