CVE-2026-64590
Estado: RecibidaSin puntuar—
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:
The call chain is:
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.
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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.
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.
Detalles técnicos trazas, registros y código del informe original
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
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
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_SYNCCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.22%
- Percentil entre todas las CVEs puntuadas: 11
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/01126abc11bcc6a45b664293b0b5df715be911d7
- https://git.kernel.org/stable/c/0449a6583c0ee76778d314e4e82f166fc97fa9d8
- https://git.kernel.org/stable/c/0db56e7eae932f8e2f3eb44ad1a63633d8f504f8
- https://git.kernel.org/stable/c/34696563461c9a23177feb6d8aff43f4c0510278
- https://git.kernel.org/stable/c/4a7c644e632741c2a3116a0d3da6c11de957a6ba
- https://git.kernel.org/stable/c/504e2b4ab97a51d56d966cd36d0997ad30b65b2d
- https://git.kernel.org/stable/c/d6552f5cff795d60e629f37513ecf23d88fd2f82
- https://git.kernel.org/stable/c/dd7f1e572f44d3d039dc77e3989f537196c3bf52
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-64590",
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"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"vulnStatus": "Received",
"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't 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 -> amdgpu_ttm_backend_bind\n -> dma_buf_map_attachment\n -> [udmabuf] map_udmabuf -> get_sg_table\n -> dma_map_sgtable(dev, sg, direction, 0) // attrs=0\n -> debug_dma_map_sg -> add_dma_entry -> 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."
}
],
"lastModified": "2026-08-23T13:16:32.443",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}