CVE-2026-64590 (GCVE-0-2026-64590)

Vulnerability from cvelistv5 – Published: 2026-08-06 07:13 – Updated: 2026-08-06 07:13
VLAI
Title
dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning
Summary
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(), 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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 284562e1f34874e267d4f499362c3816f8f6bc3f , < 0db56e7eae932f8e2f3eb44ad1a63633d8f504f8 (git)
Affected: 284562e1f34874e267d4f499362c3816f8f6bc3f , < d6552f5cff795d60e629f37513ecf23d88fd2f82 (git)
Affected: 284562e1f34874e267d4f499362c3816f8f6bc3f , < 34696563461c9a23177feb6d8aff43f4c0510278 (git)
Affected: 284562e1f34874e267d4f499362c3816f8f6bc3f , < 0449a6583c0ee76778d314e4e82f166fc97fa9d8 (git)
Affected: 284562e1f34874e267d4f499362c3816f8f6bc3f , < 504e2b4ab97a51d56d966cd36d0997ad30b65b2d (git)
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Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning\n\nWhen CONFIG_DMA_API_DEBUG_SG is enabled, importing a udmabuf into a DRM\ndriver (e.g. amdgpu for video playback in GNOME Videos / Showtime)\ntriggers a spurious warning:\n\n  DMA-API: amdgpu 0000:03:00.0: cacheline tracking EEXIST, \\\n      overlapping mappings aren\u0027t supported\n  WARNING: kernel/dma/debug.c:619 at add_dma_entry+0x473/0x5f0\n\nThe call chain is:\n\n  amdgpu_cs_ioctl\n   -\u003e amdgpu_ttm_backend_bind\n    -\u003e dma_buf_map_attachment\n     -\u003e [udmabuf] map_udmabuf -\u003e get_sg_table\n      -\u003e dma_map_sgtable(dev, sg, direction, 0)  // attrs=0\n       -\u003e debug_dma_map_sg -\u003e add_dma_entry -\u003e EEXIST\n\nThis happens because udmabuf builds a per-page scatter-gather list via\nsg_set_folio().  When begin_cpu_udmabuf() has already created an sg\ntable mapped for the misc device, and an importer such as amdgpu maps\nthe same pages for its own device via map_udmabuf(), the DMA debug\ninfrastructure sees two active mappings whose physical addresses share\ncacheline boundaries and warns about the overlap.\n\nThe DMA_ATTR_SKIP_CPU_SYNC flag suppresses this check in\nadd_dma_entry() because it signals that no CPU cache maintenance is\nperformed at map/unmap time, making the cacheline overlap harmless.\n\nAll other major dma-buf exporters already pass this flag:\n  - drm_gem_map_dma_buf() passes DMA_ATTR_SKIP_CPU_SYNC\n  - amdgpu_dma_buf_map() passes DMA_ATTR_SKIP_CPU_SYNC\n\nThe CPU sync at map/unmap time is also redundant for udmabuf:\nbegin_cpu_udmabuf() and end_cpu_udmabuf() already perform explicit\ncache synchronization via dma_sync_sgtable_for_cpu/device() when CPU\naccess is requested through the dma-buf interface.\n\nPass DMA_ATTR_SKIP_CPU_SYNC to dma_map_sgtable() and\ndma_unmap_sgtable() in udmabuf to suppress the spurious warning and\nskip the redundant sync."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-08-06T07:13:47.888Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      ],
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    "datePublished": "2026-08-06T07:13:47.888Z",
    "dateReserved": "2026-07-19T15:36:31.798Z",
    "dateUpdated": "2026-08-06T07:13:47.888Z",
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      "percentile": "0.0526"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64590\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-06T08:16:34.357\",\"lastModified\":\"2026-08-06T08:16:34.357\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ndma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning\\n\\nWhen CONFIG_DMA_API_DEBUG_SG is enabled, importing a udmabuf into a DRM\\ndriver (e.g. amdgpu for video playback in GNOME Videos / Showtime)\\ntriggers a spurious warning:\\n\\n  DMA-API: amdgpu 0000:03:00.0: cacheline tracking EEXIST, \\\\\\n      overlapping mappings aren\u0027t supported\\n  WARNING: kernel/dma/debug.c:619 at add_dma_entry+0x473/0x5f0\\n\\nThe call chain is:\\n\\n  amdgpu_cs_ioctl\\n   -\u003e amdgpu_ttm_backend_bind\\n    -\u003e dma_buf_map_attachment\\n     -\u003e [udmabuf] map_udmabuf -\u003e get_sg_table\\n      -\u003e dma_map_sgtable(dev, sg, direction, 0)  // attrs=0\\n       -\u003e debug_dma_map_sg -\u003e add_dma_entry -\u003e EEXIST\\n\\nThis happens because udmabuf builds a per-page scatter-gather list via\\nsg_set_folio().  When begin_cpu_udmabuf() has already created an sg\\ntable mapped for the misc device, and an importer such as amdgpu maps\\nthe same pages for its own device via map_udmabuf(), the DMA debug\\ninfrastructure sees two active mappings whose physical addresses share\\ncacheline boundaries and warns about the overlap.\\n\\nThe DMA_ATTR_SKIP_CPU_SYNC flag suppresses this check in\\nadd_dma_entry() because it signals that no CPU cache maintenance is\\nperformed at map/unmap time, making the cacheline overlap harmless.\\n\\nAll other major dma-buf exporters already pass this flag:\\n  - drm_gem_map_dma_buf() passes DMA_ATTR_SKIP_CPU_SYNC\\n  - amdgpu_dma_buf_map() passes DMA_ATTR_SKIP_CPU_SYNC\\n\\nThe CPU sync at map/unmap time is also redundant for udmabuf:\\nbegin_cpu_udmabuf() and end_cpu_udmabuf() already perform explicit\\ncache synchronization via dma_sync_sgtable_for_cpu/device() when CPU\\naccess is requested through the dma-buf interface.\\n\\nPass DMA_ATTR_SKIP_CPU_SYNC to dma_map_sgtable() and\\ndma_unmap_sgtable() in udmabuf to suppress the spurious warning and\\nskip the redundant sync.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/dma-buf/udmabuf.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"284562e1f34874e267d4f499362c3816f8f6bc3f\",\"lessThan\":\"0db56e7eae932f8e2f3eb44ad1a63633d8f504f8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"284562e1f34874e267d4f499362c3816f8f6bc3f\",\"lessThan\":\"d6552f5cff795d60e629f37513ecf23d88fd2f82\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"284562e1f34874e267d4f499362c3816f8f6bc3f\",\"lessThan\":\"34696563461c9a23177feb6d8aff43f4c0510278\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"284562e1f34874e267d4f499362c3816f8f6bc3f\",\"lessThan\":\"0449a6583c0ee76778d314e4e82f166fc97fa9d8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"284562e1f34874e267d4f499362c3816f8f6bc3f\",\"lessThan\":\"504e2b4ab97a51d56d966cd36d0997ad30b65b2d\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/dma-buf/udmabuf.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.148\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.96\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.39\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.4\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0449a6583c0ee76778d314e4e82f166fc97fa9d8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/0db56e7eae932f8e2f3eb44ad1a63633d8f504f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/34696563461c9a23177feb6d8aff43f4c0510278\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/504e2b4ab97a51d56d966cd36d0997ad30b65b2d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d6552f5cff795d60e629f37513ecf23d88fd2f82\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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