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CVE-2026-64098

Estado: AnalizadaAlta (7.8)—

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

drm/virtio: use uninterruptible resv lock for plane updates

virtio_gpu_cursor_plane_update() and virtio_gpu_resource_flush() lock the framebuffer BO's dma_resv via virtio_gpu_array_lock_resv() and ignore its return value. The function can fail with -EINTR from dma_resv_lock_interruptible() (signal during lock wait) or with -ENOMEM from dma_resv_reserve_fences() (fence slot allocation), leaving the resv lock not held. The queue path then walks the object array and calls dma_resv_add_fence(), which requires the lock held; with lockdep enabled this trips dma_resv_assert_held():

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Beyond the WARN, mutating the dma_resv fence list without the lock races with concurrent readers/writers and can corrupt the list.

Both call sites run inside the .atomic_update plane callback, which DRM atomic helpers do not allow to fail (by the time it runs, the commit has been signed off to userspace and there is no clean rollback path). Moving the lock acquisition to .prepare_fb was rejected because the broader lock scope deadlocks against other BO locking paths in the same atomic commit.

Introduce virtio_gpu_lock_one_resv_uninterruptible() that uses dma_resv_lock() instead of dma_resv_lock_interruptible(). This eliminates the -EINTR failure mode -- the realistic syzbot trigger -- without extending the lock hold across the commit. The helper locks a single BO and rejects nents > 1 with -EINVAL; both fix sites lock exactly one BO.

Use it from virtio_gpu_cursor_plane_update() and virtio_gpu_resource_flush(); check the return value to handle the remaining -ENOMEM case from dma_resv_reserve_fences() by freeing the objs and skipping the plane update for that frame. The framebuffer BOs touched here are not shared with other contexts and lock contention is expected to be brief, so the loss of signal-interruptibility is acceptable.

Other callers of virtio_gpu_array_lock_resv() (the ioctl paths) continue to use the interruptible variant.

The bug was reported by syzbot, triggered via fault injection (fail_nth) on the DRM_IOCTL_MODE_CURSOR path, which forces the -ENOMEM branch in dma_resv_reserve_fences().

Detalles técnicos trazas, registros y código del informe original
  WARNING: drivers/dma-buf/dma-resv.c:296 at dma_resv_add_fence+0x71e/0x840
  Call Trace:
   virtio_gpu_array_add_fence
   virtio_gpu_queue_ctrl_sgs
   virtio_gpu_queue_fenced_ctrl_buffer
   virtio_gpu_cursor_plane_update
   drm_atomic_helper_commit_planes
   drm_atomic_helper_commit_tail
   commit_tail
   drm_atomic_helper_commit
   drm_atomic_commit
   drm_atomic_helper_update_plane
   __setplane_atomic
   drm_mode_cursor_universal
   drm_mode_cursor_common
   drm_mode_cursor_ioctl
   drm_ioctl
   __x64_sys_ioctl

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Escalada local sin interacción (AV:L, PR:L, UI:N) en kernel Linux. Acceso a operación de cursor que causa race condition en dma_resv, permitiendo corromper estructuras de datos (DoS y manipulación de memoria).

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)

CWE

Referencias

JSON original (NVD)

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/virtio: use uninterruptible resv lock for plane updates\n\nvirtio_gpu_cursor_plane_update() and virtio_gpu_resource_flush() lock\nthe framebuffer BO's dma_resv via virtio_gpu_array_lock_resv() and\nignore its return value. The function can fail with -EINTR from\ndma_resv_lock_interruptible() (signal during lock wait) or with\n-ENOMEM from dma_resv_reserve_fences() (fence slot allocation),\nleaving the resv lock not held. The queue path then walks the object\narray and calls dma_resv_add_fence(), which requires the lock held;\nwith lockdep enabled this trips dma_resv_assert_held():\n\n  WARNING: drivers/dma-buf/dma-resv.c:296 at dma_resv_add_fence+0x71e/0x840\n  Call Trace:\n   virtio_gpu_array_add_fence\n   virtio_gpu_queue_ctrl_sgs\n   virtio_gpu_queue_fenced_ctrl_buffer\n   virtio_gpu_cursor_plane_update\n   drm_atomic_helper_commit_planes\n   drm_atomic_helper_commit_tail\n   commit_tail\n   drm_atomic_helper_commit\n   drm_atomic_commit\n   drm_atomic_helper_update_plane\n   __setplane_atomic\n   drm_mode_cursor_universal\n   drm_mode_cursor_common\n   drm_mode_cursor_ioctl\n   drm_ioctl\n   __x64_sys_ioctl\n\nBeyond the WARN, mutating the dma_resv fence list without the lock\nraces with concurrent readers/writers and can corrupt the list.\n\nBoth call sites run inside the .atomic_update plane callback, which\nDRM atomic helpers do not allow to fail (by the time it runs, the\ncommit has been signed off to userspace and there is no clean\nrollback path). Moving the lock acquisition to .prepare_fb was\nrejected because the broader lock scope deadlocks against other BO\nlocking paths in the same atomic commit.\n\nIntroduce virtio_gpu_lock_one_resv_uninterruptible() that uses\ndma_resv_lock() instead of dma_resv_lock_interruptible(). This\neliminates the -EINTR failure mode -- the realistic syzbot trigger\n-- without extending the lock hold across the commit. The helper\nlocks a single BO and rejects nents > 1 with -EINVAL; both fix\nsites lock exactly one BO.\n\nUse it from virtio_gpu_cursor_plane_update() and\nvirtio_gpu_resource_flush(); check the return value to handle the\nremaining -ENOMEM case from dma_resv_reserve_fences() by freeing\nthe objs and skipping the plane update for that frame. The\nframebuffer BOs touched here are not shared with other contexts\nand lock contention is expected to be brief, so the loss of\nsignal-interruptibility is acceptable.\n\nOther callers of virtio_gpu_array_lock_resv() (the ioctl paths)\ncontinue to use the interruptible variant.\n\nThe bug was reported by syzbot, triggered via fault injection\n(fail_nth) on the DRM_IOCTL_MODE_CURSOR path, which forces the\n-ENOMEM branch in dma_resv_reserve_fences()."
    }
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  "lastModified": "2026-08-11T16:07:46.703",
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