{"id":"CVE-2026-93275","summary":"perf/x86/intel/pt: Fix stop/start with no update","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/pt: Fix stop/start with no update\n\nIf pt_event_stop() is called without PERF_EF_UPDATE flag, then\nperf_aux_output_end() is not called.  A subsequent call to pt_event_start()\nwill call perf_aux_output_begin() again which violates the rule against\nnesting and triggers a WARNING in perf_aux_output_begin().\n\nOriginally, pt_event_stop() was never called without PERF_EF_UPDATE,\nbecause the only code paths to do so are from event overflow, and Intel PT\ndoes not do that.\n\nHowever the introduction of group throttling by commit 9734e25fbf5ae\n(\"perf: Fix the throttle logic for a group\") meant that an Intel PT event\ncould be throttled if it was part of a group.  Throttling calls PMU\n -\u003estop() / -\u003estart() callbacks without flags.\n\nAn example is when AUX area sampling is used. The following commands\nhit the issue:\n\n  echo 10000 \u003e /proc/sys/kernel/perf_event_max_sample_rate\n\n  perf record -F32000 --aux-sample -e '{intel_pt//u,cycles:u}' \\\n  -- bash -c 'for i in `seq 1 100000` ; do true ; done'\n\nUse PERF_HES_UPTODATE to track whether perf_aux_output_begin() and\nperf_aux_output_end() are balanced.  A cleared PERF_HES_UPTODATE bit\nindicates that an AUX output context is still open.\n\nAmend pt_event_start() / pt_event_stop() accordingly so that begin/end\nstay balanced:\n\n - In non-snapshot mode, stop() always closes the buffer (the buffer may\n   have run out of space, and that accounting is done by the update), so\n   a following start() opens a fresh one as before.\n\n - In snapshot/overwrite mode, stop() without PERF_EF_UPDATE leaves the\n   buffer open so that pt_event_snapshot_aux() can still copy from it,\n   and start() then only re-enables tracing instead of calling\n   perf_aux_output_begin() again.\n\nNote that pt_event_del() calls pt_event_stop() with PERF_EF_UPDATE flag set\n(as is required by the documentation), so a final call to\nperf_aux_output_end() is assured.","modified":"2026-09-26T03:48:31.259063432Z","published":"2026-09-24T15:52:17.064Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93275.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/304844b5545f444d523286da8228a1cbc46ffffa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9b919fb5512f256e9e0604faf960b2bb98aab454"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cab5015ee3f25f789b4a368f2abfa65536576b78"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93275.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93275"},{"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":"52ca9ced3f70779589e6ecc329baffe69d8f5f7a"},{"fixed":"9b919fb5512f256e9e0604faf960b2bb98aab454"},{"fixed":"cab5015ee3f25f789b4a368f2abfa65536576b78"},{"fixed":"304844b5545f444d523286da8228a1cbc46ffffa"},{"fixed":"2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-93275.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.1.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-93275.json"}}],"schema_version":"1.9.0"}