{
  "cveId": "CVE-2026-64590",
  "url": "https://patchblox.com/security/cve/CVE-2026-64590",
  "summary": "CVE-2026-64590 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-64590, released August 6, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning",
  "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\u0027t supported   WARNING: kernel/dma/debug.c:619 at add_dma_entry\u002B0x473/0x5f0  The call chain is:    amdgpu_cs_ioctl    -\u003E amdgpu_ttm_backend_bind     -\u003E dma_buf_map_attachment      -\u003E [udmabuf] map_udmabuf -\u003E get_sg_table       -\u003E dma_map_sgtable(dev, sg, direction, 0)  // attrs=0        -\u003E debug_dma_map_sg -\u003E add_dma_entry -\u003E 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(), the DMA debug infrastructure sees two active mappings whose physical addresses share cacheline boundaries and warns about the overlap.  The DMA_ATTR_SKIP_CPU_SYNC flag suppresses this check in add_dma_entry() because it signals that no CPU cache maintenance is performed at map/unmap time, making the cacheline overlap harmless.  All other major dma-buf exporters already pass this flag:   - drm_gem_map_dma_buf() passes DMA_ATTR_SKIP_CPU_SYNC   - amdgpu_dma_buf_map() passes DMA_ATTR_SKIP_CPU_SYNC  The CPU sync at map/unmap time is also redundant for udmabuf: begin_cpu_udmabuf() and end_cpu_udmabuf() already perform explicit cache synchronization via dma_sync_sgtable_for_cpu/device() when CPU access is requested through the dma-buf interface.  Pass DMA_ATTR_SKIP_CPU_SYNC to dma_map_sgtable() and dma_unmap_sgtable() in udmabuf to suppress the spurious warning and skip the redundant sync.",
  "published": "2026-08-06T08:16:34Z",
  "severity": "Important",
  "cvss": 7.1,
  "epss": 0.00165,
  "epssPercentile": 0.057,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64590",
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.1.187-1",
      "fix": "DEBIAN-CVE-2026-64590",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64590",
      "released": "2026-08-06T15:13:07Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.96-1",
      "fix": "DEBIAN-CVE-2026-64590",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64590",
      "released": "2026-08-06T15:13:07Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.4-1",
      "fix": "DEBIAN-CVE-2026-64590",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64590",
      "released": "2026-08-06T15:13:07Z"
    },
    {
      "platform": "linux",
      "product": "linux-6.12",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.12.100-1~deb12u1",
      "fix": "DEBIAN-CVE-2026-64590",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64590",
      "released": "2026-08-06T15:13:07Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}