CVE-2026-68266
Estado: RecibidaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
drm/xe: Hold a dma-buf reference for imported BOs
An imported dma-buf BO is created as a ttm_bo_type_sg BO whose reservation object is the exporter's dma_buf->resv. The importer, however, only takes a dma-buf reference after a successful dma_buf_dynamic_attach(). Until then nothing keeps the exporter alive, so if the exporter is freed while the BO still references its resv, a later access to that resv is a use-after-free:
This can be reached on two paths:
- dma_buf_dynamic_attach() fails, or - ttm_bo_init_reserved() fails during BO creation.
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In both cases the BO already has bo->base.resv pointing at the exporter resv, and sg BOs are always torn down via ttm_bo_delayed_delete(), which locks bo->base.resv asynchronously - potentially after the exporter has been freed.
Take the dma-buf reference in xe_bo_init_locked(), before ttm_bo_init_reserved(), so it also covers a creation failure there, and release it in xe_ttm_bo_destroy(). The reference is held for the whole BO lifetime, keeping the shared resv alive on every path.
(cherry picked from commit 3516f3fae6be35642f8f06f8a218da6425c0306a)
Detalles técnicos trazas, registros y código del informe original
Oops: general protection fault, probably for non-canonical address
0x6b6b6b6b6b6b6b9c
Workqueue: ttm ttm_bo_delayed_delete [ttm]
RIP: 0010:mutex_can_spin_on_owner+0x3f/0xc0
v2:
- Reworked the fix to avoid creating the imported sg BO before
dma_buf_dynamic_attach() succeeds.
- Attach with importer_priv == NULL and make invalidate_mappings ignore
incomplete imports.
v3:
- Dropped the xe-side reordering approach since importer_priv must be
valid when dma_buf_dynamic_attach() publishes the attachment.
- Per Christian's suggestion on the v1 thread, keyed the check on
import_attach rather than removing the sg guard entirely.
- Fixes both xe and amdgpu in a single TTM patch.
v4:
- Moved import_attach check to after dma_resv_copy_fences() so fences
are copied before returning for successful imports (Thomas).
- Removed exporter-alive claim from commit message (Thomas).
v5:
- Add drm/xe patch to keep imported sg BOs off the LRU before attach
succeeds; the TTM fix alone is not sufficient for xe if the BO is
already LRU-visible. (Thomas)
v4 patch:
https://patchwork.freedesktop.org/patch/736663/?series=169129&rev=2
- Patch 1 (drm/ttm) carries Christian's Reviewed-by from v4.
v6:
- Reworked the fix based on Thomas' suggestion. Instead of the TTM resv
individualization (v1-v5) plus the xe off-LRU/placement handling (v5),
just hold a dma-buf reference for the imported BO lifetime so the
shared resv can never be freed while the BO still references it.
Single xe patch, no TTM change. (Thomas)
- Take the reference in xe_bo_init_locked() before ttm_bo_init_reserved()
so a TTM creation failure is covered too (Thomas).
- Dropped the v5 series (drm/ttm + drm/xe off-LRU); the off-LRU approach
also regressed in CI BAT via ttm_bo_pipeline_gutting() creating a ghost
BO that outlived the exporter.
Link to v5: https://patchwork.freedesktop.org/series/169984/
v7:
- Move changelog above --- so it stays in the commit message.
- Reorder changelog entries oldest-to-newest. (Thomas)CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.13%
- Percentil entre todas las CVEs puntuadas: 2
- 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).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1499.004Application or System Exploitationimpact75 %
Vulnerabilidad de use-after-free en kernel Linux (AV:L, PR:L, sin UI) que permite escalada de privilegios local explotando gestión defectuosa de referencias en dma-buf; impacta con DoS por acceso a memoria liberada.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-68266",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "dd08ebf6c3525a7ea2186e636df064ea47281987",
"lessThan": "c22d65d62b3318e237c0e5b1177d90ab83d9fe06",
"versionType": "git"
},
{
"status": "affected",
"version": "dd08ebf6c3525a7ea2186e636df064ea47281987",
"lessThan": "c1954c66662de477a8f4309335b775f7b07bd28b",
"versionType": "git"
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{
"status": "affected",
"version": "dd08ebf6c3525a7ea2186e636df064ea47281987",
"lessThan": "ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48",
"versionType": "git"
},
{
"status": "affected",
"version": "dd08ebf6c3525a7ea2186e636df064ea47281987",
"lessThan": "62775525a27c3b0d56382e08ba81ee2d322058b6",
"versionType": "git"
}
],
"programFiles": [
"drivers/gpu/drm/xe/xe_bo.c",
"drivers/gpu/drm/xe/xe_bo.h",
"drivers/gpu/drm/xe/xe_bo_types.h",
"drivers/gpu/drm/xe/xe_dma_buf.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.103",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/gpu/drm/xe/xe_bo.c",
"drivers/gpu/drm/xe/xe_bo.h",
"drivers/gpu/drm/xe/xe_bo_types.h",
"drivers/gpu/drm/xe/xe_dma_buf.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-10T13:20:15.493",
"references": [
{
"url": "https://git.kernel.org/stable/c/62775525a27c3b0d56382e08ba81ee2d322058b6",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/ba8c4cbb31c6f81fa5b12d6e28f1f706040aff48",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c1954c66662de477a8f4309335b775f7b07bd28b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c22d65d62b3318e237c0e5b1177d90ab83d9fe06",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: Hold a dma-buf reference for imported BOs\n\nAn imported dma-buf BO is created as a ttm_bo_type_sg BO whose\nreservation object is the exporter's dma_buf->resv. The importer,\nhowever, only takes a dma-buf reference after a successful\ndma_buf_dynamic_attach(). Until then nothing keeps the exporter alive,\nso if the exporter is freed while the BO still references its resv, a\nlater access to that resv is a use-after-free:\n\n Oops: general protection fault, probably for non-canonical address\n 0x6b6b6b6b6b6b6b9c\n Workqueue: ttm ttm_bo_delayed_delete [ttm]\n RIP: 0010:mutex_can_spin_on_owner+0x3f/0xc0\n\nThis can be reached on two paths:\n\n - dma_buf_dynamic_attach() fails, or\n - ttm_bo_init_reserved() fails during BO creation.\n\nIn both cases the BO already has bo->base.resv pointing at the exporter\nresv, and sg BOs are always torn down via ttm_bo_delayed_delete(), which\nlocks bo->base.resv asynchronously - potentially after the exporter has\nbeen freed.\n\nTake the dma-buf reference in xe_bo_init_locked(), before\nttm_bo_init_reserved(), so it also covers a creation failure there, and\nrelease it in xe_ttm_bo_destroy(). The reference is held for the whole\nBO lifetime, keeping the shared resv alive on every path.\n\nv2:\n - Reworked the fix to avoid creating the imported sg BO before\n dma_buf_dynamic_attach() succeeds.\n - Attach with importer_priv == NULL and make invalidate_mappings ignore\n incomplete imports.\n\nv3:\n - Dropped the xe-side reordering approach since importer_priv must be\n valid when dma_buf_dynamic_attach() publishes the attachment.\n - Per Christian's suggestion on the v1 thread, keyed the check on\n import_attach rather than removing the sg guard entirely.\n - Fixes both xe and amdgpu in a single TTM patch.\n\nv4:\n - Moved import_attach check to after dma_resv_copy_fences() so fences\n are copied before returning for successful imports (Thomas).\n - Removed exporter-alive claim from commit message (Thomas).\n\nv5:\n - Add drm/xe patch to keep imported sg BOs off the LRU before attach\n succeeds; the TTM fix alone is not sufficient for xe if the BO is\n already LRU-visible. (Thomas)\n v4 patch:\n https://patchwork.freedesktop.org/patch/736663/?series=169129&rev=2\n - Patch 1 (drm/ttm) carries Christian's Reviewed-by from v4.\n\nv6:\n - Reworked the fix based on Thomas' suggestion. Instead of the TTM resv\n individualization (v1-v5) plus the xe off-LRU/placement handling (v5),\n just hold a dma-buf reference for the imported BO lifetime so the\n shared resv can never be freed while the BO still references it.\n Single xe patch, no TTM change. (Thomas)\n - Take the reference in xe_bo_init_locked() before ttm_bo_init_reserved()\n so a TTM creation failure is covered too (Thomas).\n - Dropped the v5 series (drm/ttm + drm/xe off-LRU); the off-LRU approach\n also regressed in CI BAT via ttm_bo_pipeline_gutting() creating a ghost\n BO that outlived the exporter.\n Link to v5: https://patchwork.freedesktop.org/series/169984/\n\nv7:\n - Move changelog above --- so it stays in the commit message.\n - Reorder changelog entries oldest-to-newest. (Thomas)\n\n(cherry picked from commit 3516f3fae6be35642f8f06f8a218da6425c0306a)"
}
],
"lastModified": "2026-08-17T05:18:29.100",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}