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CVE-2022-49963

Estado: ModificadaMedia (5.5)—

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

drm/i915/ttm: fix CCS handling

Crucible + recent Mesa seems to sometimes hit:

GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER)

And it looks like we can also trigger this with gem_lmem_swapping, if we modify the test to use slightly larger object sizes.

Looking closer it looks like we have the following issues in migrate_copy():

So it looks like our copy handling for any object > 8M (which is our CHUNK_SZ) is currently broken on DG2.

Testcase: igt@gem_lmem_swapping (cherry picked from commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)

Detalles técnicos trazas, registros y código del informe original
  - We are using plain integer in various places, which we can easily
    overflow with a large object.

  - We pass the entire object size (when the src is lmem) into
    emit_pte() and then try to copy it, which doesn't work, since we
    only have a few fixed sized windows in which to map the pages and
    perform the copy. With an object > 8M we therefore aren't properly
    copying the pages. And then with an object > 64M we trigger the
    GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER).

CVSS

Probabilidad de explotación (EPSS)

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)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2022-49963",
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  "published": "2025-06-18T11:15:23.570",
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    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/i915/ttm: fix CCS handling\n\nCrucible + recent Mesa seems to sometimes hit:\n\nGEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER)\n\nAnd it looks like we can also trigger this with gem_lmem_swapping, if we\nmodify the test to use slightly larger object sizes.\n\nLooking closer it looks like we have the following issues in\nmigrate_copy():\n\n  - We are using plain integer in various places, which we can easily\n    overflow with a large object.\n\n  - We pass the entire object size (when the src is lmem) into\n    emit_pte() and then try to copy it, which doesn't work, since we\n    only have a few fixed sized windows in which to map the pages and\n    perform the copy. With an object > 8M we therefore aren't properly\n    copying the pages. And then with an object > 64M we trigger the\n    GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER).\n\nSo it looks like our copy handling for any object > 8M (which is our\nCHUNK_SZ) is currently broken on DG2.\n\nTestcase: igt@gem_lmem_swapping\n(cherry picked from commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: drm/i915/ttm: corrección del manejo de CCS Crucible + Mesa reciente parece a veces afectar: GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER) Y parece que también podemos activar esto con gem_lmem_swapping, si modificamos la prueba para usar tamaños de objeto ligeramente mayores. Mirando más de cerca, parece que tenemos los siguientes problemas en migration_copy(): - Estamos usando un entero simple en varios lugares, que podemos desbordar fácilmente con un objeto grande. - Pasamos el tamaño completo del objeto (cuando el src es lmem) a emit_pte() y luego intentamos copiarlo, lo cual no funciona, ya que solo tenemos unas pocas ventanas de tamaño fijo en las que mapear las páginas y realizar la copia. Con un objeto > 8M, por lo tanto, no estamos copiando correctamente las páginas. Y luego, con un objeto > 64M, activamos GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER). Por lo tanto, parece que nuestra gestión de copias para cualquier objeto > 8M (que es nuestro CHUNK_SZ) está actualmente inactiva en DG2. Caso de prueba: igt@gem_lmem_swapping (seleccionado de el commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)"
    }
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  "lastModified": "2026-08-04T10:18:01.137",
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