CVE-2026-64590

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning

When CONFIG_DMA_API_DEBUG_SG is enabled, importing a udmabuf into a DRM

driver (e.g. amdgpu for video playback in GNOME Videos / Showtime)

triggers a spurious warning:

DMA-API: amdgpu 0000:03:00.0: cacheline tracking EEXIST, \

overlapping mappings aren't supported

WARNING: kernel/dma/debug.c:619 at add_dma_entry+0x473/0x5f0

The call chain is:

amdgpu_cs_ioctl

-> amdgpu_ttm_backend_bind

-> dma_buf_map_attachment

-> [udmabuf] map_udmabuf -> get_sg_table

-> dma_map_sgtable(dev, sg, direction, 0) // attrs=0

-> debug_dma_map_sg -> add_dma_entry -> EEXIST

This happens because udmabuf builds a per-page scatter-gather list via

sg_set_folio(). When begin_cpu_udmabuf() has already created an sg

table mapped for the misc device, and an importer such as amdgpu maps

the same pages for its own device via map_udmabuf()

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References