CVE-2026-63863 (GCVE-0-2026-63863)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:04 – Updated: 2026-08-05 12:36
VLAI
Title
drm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm()
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm() There is a unbalanced lock/unlock to gpusvm notifier lock: [ 931.045868] ===================================== [ 931.046509] WARNING: bad unlock balance detected! [ 931.047149] 6.19.0-rc6+xe-**************** #9 Tainted: G U [ 931.048150] ------------------------------------- [ 931.048790] kworker/u5:0/51 is trying to release lock (&gpusvm->notifier_lock) at: [ 931.049801] [<ffffffffa090c0d8>] drm_gpusvm_scan_mm+0x188/0x460 [drm_gpusvm_helper] [ 931.050802] but there are no more locks to release! [ 931.051463] The drm_gpusvm_notifier_unlock() sits under err_free label and the first jump to err_free is just before calling the drm_gpusvm_notifier_lock() causing unbalanced unlock.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f1d08a5864822684773105c60528e2abb577ca6c , < 8efaa47a871662a8c21b819cec60786f7ef17ab4 (git)
Affected: f1d08a5864822684773105c60528e2abb577ca6c , < d287dee565c3c32e1ed76ec1847af46809c29b90 (git)
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Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
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          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_gpusvm.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm()\n\nThere is a unbalanced lock/unlock to gpusvm notifier lock:\n[  931.045868] =====================================\n[  931.046509] WARNING: bad unlock balance detected!\n[  931.047149] 6.19.0-rc6+xe-**************** #9 Tainted: G     U\n[  931.048150] -------------------------------------\n[  931.048790] kworker/u5:0/51 is trying to release lock (\u0026gpusvm-\u003enotifier_lock) at:\n[  931.049801] [\u003cffffffffa090c0d8\u003e] drm_gpusvm_scan_mm+0x188/0x460 [drm_gpusvm_helper]\n[  931.050802] but there are no more locks to release!\n[  931.051463]\n\nThe drm_gpusvm_notifier_unlock() sits under err_free label and the\nfirst jump to err_free is just before calling the\ndrm_gpusvm_notifier_lock() causing unbalanced unlock."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable code is only reached via Intel Xe DRM ioctls (DRM_XE_VM_BIND prefetch, GPU page-fault handling) on /dev/dri/renderD*, which require local access to the GPU device node.\nAC:L - An attacker can reliably trigger the bug by racing CPU memory operations (munmap/mremap/mprotect) against GPU SVM VRAM migration to force hmm_range_fault() to return an error or time out on -EBUSY, hitting the err_free path without holding notifier_lock.\nPR:L - Exploitation requires opening the DRM render node (DRM_RENDER_ALLOW), which is available to unprivileged users in the render group on typical desktop and cloud GPU instances, not root or capabilities.\nUI:N - No victim interaction is required; the attacker triggers the condition through their own GPU VM bindings, compute submissions, and concurrent memory manipulation.\nS:C - Corrupting notifier_lock breaks the documented IOMMU security model for GPU SVM, allowing GPU DMA operations to proceed without proper invalidation synchronization and potentially accessing host memory outside the attacker\u0027s GPU context.\nC:H - Rwsem corruption from the spurious unlock can desynchronize invalidation from migration, enabling races where the GPU reads stale or freed pages that may have been reallocated, constituting arbitrary memory disclosure.\nI:H - The same lock corruption can allow GPU DMA writes to pages during or after invalidation races, providing a path to arbitrary memory corruption and potential privilege escalation.\nA:H - The bug triggers a kernel lockdep warning (\"bad unlock balance detected\") and rwsem corruption can cause kernel oops, hangs, or panic during subsequent notifier_lock operations."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:36:39.194Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/8efaa47a871662a8c21b819cec60786f7ef17ab4"
        },
        {
          "url": "https://git.kernel.org/stable/c/d287dee565c3c32e1ed76ec1847af46809c29b90"
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      ],
      "title": "drm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63863",
    "datePublished": "2026-07-19T14:04:49.967Z",
    "dateReserved": "2026-07-19T07:54:57.017Z",
    "dateUpdated": "2026-08-05T12:36:39.194Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-09-21",
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      "percentile": "0.02432"
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        "descriptions": [
          {
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm()\n\nThere is a unbalanced lock/unlock to gpusvm notifier lock:\n[  931.045868] =====================================\n[  931.046509] WARNING: bad unlock balance detected!\n[  931.047149] 6.19.0-rc6+xe-**************** #9 Tainted: G     U\n[  931.048150] -------------------------------------\n[  931.048790] kworker/u5:0/51 is trying to release lock (\u0026gpusvm-\u003enotifier_lock) at:\n[  931.049801] [\u003cffffffffa090c0d8\u003e] drm_gpusvm_scan_mm+0x188/0x460 [drm_gpusvm_helper]\n[  931.050802] but there are no more locks to release!\n[  931.051463]\n\nThe drm_gpusvm_notifier_unlock() sits under err_free label and the\nfirst jump to err_free is just before calling the\ndrm_gpusvm_notifier_lock() causing unbalanced unlock."
          }
        ],
        "id": "CVE-2026-63863",
        "lastModified": "2026-07-27T17:44:23.777",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
                "version": "3.1"
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-07-19T15:16:53.200",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/8efaa47a871662a8c21b819cec60786f7ef17ab4"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/d287dee565c3c32e1ed76ec1847af46809c29b90"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Awaiting Analysis"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-21T19:05:56+00:00",
      "cve": "CVE-2026-63863",
      "id": "CVE-2026-63863",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "108",
      "product_status:known_not_affected": "166",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: drm/gpusvm: Fix unbalanced unlock in drm_gpusvm_scan_mm()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63863.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.