perf/core: Fix a refcount leak in attach_perf_ctx_data()

{
  "id": "2f53f02b0eec9c1caf86ba482d978dc905baec7b16cb3bc94402261162fb07b0",
  "url": "https://osv.dev/vulnerability/CVE-2026-98552",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "perf/core: Fix a refcount leak in attach_perf_ctx_data()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix a refcount leak in attach_perf_ctx_data() The attach_perf_ctx_data() can race on global and !global cases. The global case is protected by global_ctx_data_rwsem and shares a single reference count using perf_ctx_data.global field. But when it races with !global case, it may miss to set the global field and result in a reference count leak. CPU1 CPU2 ---------------------------------------------------------------- attach_task_ctx_data(.global=1) attach_task_ctx_data(.global=0) cd1 = alloc_perf_ctx_data(); cd2 = alloc_perf_ctx_data(); // { .global = 0, .refcount = 1 }; try_cmpxchg(); // success, // task->perf_ctx_data = cd2 try_cmpxhg(); // fail; old = cd2 refcount_inc_not_zero(&old->refcount); // success // old.refcount = 2 free_perf_ctx_data(cd1); Then later detach_global_ctx_data() will see the data but it's not marked as global, so it won't call detach_task_ctx_data().",
    "evidence": "osv:CVE-2026-98552",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98552",
      "aliases": [
        "CVE-2026-98552"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "506e64e710ff9573fd2b86686528762b7901b5e4"
                },
                {
                  "fixed": "23250517cd475367653f1e99396967f54c6f1b7c"
                },
                {
                  "fixed": "5286d4eb5cd7e10d7d93c3cc596e18bc8ad80f72"
                },
                {
                  "fixed": "cca4980630b3c7a85f53cb43c6018184ce5d4e37"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98552.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
                },
                {
                  "fixed": "6.18.55"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98552.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.244209400Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/23250517cd475367653f1e99396967f54c6f1b7c",
        "https://git.kernel.org/stable/c/5286d4eb5cd7e10d7d93c3cc596e18bc8ad80f72",
        "https://git.kernel.org/stable/c/cca4980630b3c7a85f53cb43c6018184ce5d4e37",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98552.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98552",
        "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/2026/98xxx/CVE-2026-98552.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98552",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 496312,
  "published_at": "2026-10-18T15:18:19.81+00:00"
}