CVE-2026-64590

A flaw was found in the Linux kernel's dma-buf subsystem, specifically within the udmabuf component. When the CONFIG_DMA_API_DEBUG_SG option is enabled, importing a udmabuf into a Direct Rendering Manager (DRM) driver can trigger a spurious warning about overlapping cacheline mappings. This occurs because udmabuf does not correctly pass the DMA_ATTR_SKIP_CPU_SYNC flag during scatter-gather list mapping, leading to redundant CPU cache synchronization and an unnecessary debugging alert. While the cacheline overlap itself is harmless when the correct flag is used, the presence of this warning indicates an inefficiency in resource handling within the kernel's DMA (Direct Memory Access) API debugging infrastructure.

This vulnerability is assessed with a Low impact because triggering the condition requires DMA debug tracking to be enabled and only results in a harmless kernel warning without memory corruption. In Red Hat Enterprise Linux environments, production kernels typically disable these debug checks, and the issue requires local execution involving user-space DMA buffers mapped by display drivers. Because the underlying cacheline mappings remain functionally safe, there is no compromise to system confidentiality, integrity, or availability.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.