{"id":"CVE-2025-37878","summary":"perf/core: Fix WARN_ON(!ctx) in __free_event() for partial init","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Fix WARN_ON(!ctx) in __free_event() for partial init\n\nMove the get_ctx(child_ctx) call and the child_event-\u003ectx assignment to\noccur immediately after the child event is allocated. Ensure that\nchild_event-\u003ectx is non-NULL before any subsequent error path within\ninherit_event calls free_event(), satisfying the assumptions of the\ncleanup code.\n\nDetails:\n\nThere's no clear Fixes tag, because this bug is a side-effect of\nmultiple interacting commits over time (up to 15 years old), not\na single regression.\n\nThe code initially incremented refcount then assigned context\nimmediately after the child_event was created. Later, an early\nvalidity check for child_event was added before the\nrefcount/assignment. Even later, a WARN_ON_ONCE() cleanup check was\nadded, assuming event-\u003ectx is valid if the pmu_ctx is valid.\nThe problem is that the WARN_ON_ONCE() could trigger after the initial\ncheck passed but before child_event-\u003ectx was assigned, violating its\nprecondition. The solution is to assign child_event-\u003ectx right after\nits initial validation. This ensures the context exists for any\nsubsequent checks or cleanup routines, resolving the WARN_ON_ONCE().\n\nTo resolve it, defer the refcount update and child_event-\u003ectx assignment\ndirectly after child_event-\u003epmu_ctx is set but before checking if the\nparent event is orphaned. The cleanup routine depends on\nevent-\u003epmu_ctx being non-NULL before it verifies event-\u003ectx is\nnon-NULL. This also maintains the author's original intent of passing\nin child_ctx to find_get_pmu_context before its refcount/assignment.\n\n[ mingo: Expanded the changelog from another email by Gabriel Shahrouzi. ]","modified":"2026-03-20T12:42:32.221955Z","published":"2025-05-09T06:45:42.459Z","related":["MGASA-2025-0182","MGASA-2025-0183"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37878.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0ba3a4ab76fd3367b9cb680cad70182c896c795c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/90dc6c1e3b200812da8d0aa030e1b7fda8226d0e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb56cd11feabf99e08bc18960700a53322ffcea7"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37878.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-37878"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7ef5aa081f989ecfecc1df02068a80aebbd3ec31"},{"fixed":"90dc6c1e3b200812da8d0aa030e1b7fda8226d0e"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1209b0b29fd472e7dbd2b06544b019dd9f9b7e51"},{"fixed":"cb56cd11feabf99e08bc18960700a53322ffcea7"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c70ca298036c58a88686ff388d3d367e9d21acf0"},{"fixed":"0ba3a4ab76fd3367b9cb680cad70182c896c795c"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"315a50c6b1c6ce191f19f3372935d8e2ed9b53a6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-37878.json"}}],"schema_version":"1.7.5"}