drm/v3d: Reject empty multisync extension to prevent infinite loop

{
  "id": "97551bc9727cc658b9311343d9f74fb7a6a1640c225ee6ad5257acbb84c1fb7c",
  "url": "https://osv.dev/vulnerability/CVE-2026-46314",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "drm/v3d: Reject empty multisync extension to prevent infinite loop",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: drm/v3d: Reject empty multisync extension to prevent infinite loop v3d_get_extensions() walks a userspace-provided singly-linked list of ioctl extensions without any bound on the chain length. A local user can craft a self-referential extension (ext->next == &ext) with zero in_sync_count and out_sync_count, which bypasses the existing duplicate- extension guard: if (se->in_sync_count || se->out_sync_count) return -EINVAL; The guard never fires because v3d_get_multisync_post_deps() returns immediately when count is zero, leaving both fields at zero on every iteration. The result is an infinite loop in kernel context, blocking the calling thread and pegging a CPU core indefinitely. Fix this by rejecting a multisync extension where both in_sync_count and out_sync_count are zero in v3d_get_multisync_submit_deps(). An empty multisync carries no synchronization information and serves no useful purpose, so returning -EINVAL for such an extension is the correct defense against this attack vector.",
    "evidence": "osv:CVE-2026-46314",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.176",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.33",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-46314",
      "aliases": [
        "CVE-2026-46314"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "e4165ae8304e5ea822fbe5909dd3be5445c058b7"
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                {
                  "fixed": "309abbddeca0c12714721928a819ef45e5710998"
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                {
                  "fixed": "4fa42a249e8cd6ed17aea04e5695b6e9001f2433"
                },
                {
                  "fixed": "9c5164781cb388d219d8f49fa0f0b04cf86ad544"
                },
                {
                  "fixed": "fb44d589bf3148e13452185a6e772a7efbf2d684"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46314.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.176"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.18.33"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46314.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.764517164Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/309abbddeca0c12714721928a819ef45e5710998",
        "https://git.kernel.org/stable/c/4fa42a249e8cd6ed17aea04e5695b6e9001f2433",
        "https://git.kernel.org/stable/c/9c5164781cb388d219d8f49fa0f0b04cf86ad544",
        "https://git.kernel.org/stable/c/fb44d589bf3148e13452185a6e772a7efbf2d684",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46314.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46314",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46314.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46314",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 491303,
  "published_at": "2026-06-08T15:50:45.305+00:00"
}