{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-21895",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2025-21895"
  ],
  "published": "2025-04-01T15:31:03Z",
  "summary": "perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Order the PMU list to fix warning about unordered pmu_ctx_list\n\nSyskaller triggers a warning due to prev_epc->pmu != next_epc->pmu in\nperf_event_swap_task_ctx_data(). vmcore shows that two lists have the same\nperf_event_pmu_context, but not in the same order.\n\nThe problem is that the order of pmu_ctx_list for the parent is impacted by\nthe time when an event/PMU is added. While the order for a child is\nimpacted by the event order in the pinned_groups and flexible_groups. So\nthe order of pmu_ctx_list in the parent and child may be different.\n\nTo fix this problem, insert the perf_event_pmu_context to its proper place\nafter iteration of the pmu_ctx_list.\n\nThe follow testcase can trigger above warning:\n\n # perf record -e cycles --call-graph lbr -- taskset -c 3 ./a.out &\n # perf stat -e cpu-clock,cs -p xxx // xxx is the pid of a.out\n\n test.c\n\n void main() {\n        int count = 0;\n        pid_t pid;\n\n        printf(\"%d running\\n\", getpid());\n        sleep(30);\n        printf(\"running\\n\");\n\n        pid = fork();\n        if (pid == -1) {\n                printf(\"fork error\\n\");\n                return;\n        }\n        if (pid == 0) {\n                while (1) {\n                        count++;\n                }\n        } else {\n                while (1) {\n                        count++;\n                }\n        }\n }\n\nThe testcase first opens an LBR event, so it will allocate task_ctx_data,\nand then open tracepoint and software events, so the parent context will\nhave 3 different perf_event_pmu_contexts. On inheritance, child ctx will\ninsert the perf_event_pmu_context in another order and the warning will\ntrigger.\n\n[ mingo: Tidied up the changelog. ]",
  "affected": [
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      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
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        "1:6.6.51-1+rpt2",
        "1:6.6.51-1+rpt3",
        "1:6.6.62-1+rpt1",
        "1:6.6.74-1+rpt1"
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  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-21895"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f0c3971405cef6892844016aa710121a02da3a23"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7d582eb6e4e100959ba07083d7563453c8c2a343"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3e812a70732d84b7873cea61a7f6349b9a9dcbf5"
    },
    {
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      "url": "https://git.kernel.org/stable/c/2016066c66192a99d9e0ebf433789c490a6785a2"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-05-12T04:54:46Z"
  }
}