{"vulnerability": "CVE-2025-21895", "sightings": [{"uuid": "8e7bda28-1e52-4bb5-906f-0a6aee91c47a", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21895", "type": "seen", "source": "https://gist.github.com/Darkcrai86/bff19b21f229556d276a1ee6e52b74d5", "content": "", "creation_timestamp": "2025-09-24T11:16:15.000000Z"}, {"uuid": "7a74dedb-c3cd-45b5-a8b7-d313eaa5ece0", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2025-21895", "type": "published-proof-of-concept", "source": "https://t.me/DarkWebInformer_CVEAlerts/9925", "content": "\ud83d\udd17 DarkWebInformer.com - Cyber Threat Intelligence\n\ud83d\udccc CVE ID: CVE-2025-21895\n\ud83d\udd25 CVSS Score: N/A\n\ud83d\udd39 Description: 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. ]\n\ud83d\udccf Published: 2025-04-01T15:26:48.607Z\n\ud83d\udccf Modified: 2025-04-01T15:26:48.607Z\n\ud83d\udd17 References:\n1. https://git.kernel.org/stable/c/f0c3971405cef6892844016aa710121a02da3a23\n2. https://git.kernel.org/stable/c/7d582eb6e4e100959ba07083d7563453c8c2a343\n3. https://git.kernel.org/stable/c/3e812a70732d84b7873cea61a7f6349b9a9dcbf5\n4. https://git.kernel.org/stable/c/2016066c66192a99d9e0ebf433789c490a6785a2", "creation_timestamp": "2025-04-01T15:32:45.000000Z"}]}