perf/x86/intel/pt: Fix stop/start with no update

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93275
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-24 16:17:24 UTC
Updated2026-09-24 16:17:24 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: perf/x86/intel/pt: Fix stop/start with no update If pt_event_stop() is called without PERF_EF_UPDATE flag, then perf_aux_output_end() is not called. A subsequent call to pt_event_start() will call perf_aux_output_begin() again which violates the rule against nesting and triggers a WARNING in perf_aux_output_begin(). Originally, pt_event_stop() was never called without PERF_EF_UPDATE, because the only code paths to do so are from event overflow, and Intel PT does not do that. However the introduction of group throttling by commit 9734e25fbf5ae ("perf: Fix the throttle logic for a group") meant that an Intel PT event could be throttled if it was part of a group. Throttling calls PMU ->stop() / ->start() callbacks without flags. An example is when AUX area sampling is used. The following commands hit the issue: echo 10000 > /proc/sys/kernel/perf_event_max_sample_rate perf record -F32000 --aux-sample -e '{intel_pt//u,cycles:u}' \ -- bash -c 'for i in `seq 1 100000` ; do true ; done' Use PERF_HES_UPTODATE to track whether perf_aux_output_begin() and perf_aux_output_end() are balanced. A cleared PERF_HES_UPTODATE bit indicates that an AUX output context is still open. Amend pt_event_start() / pt_event_stop() accordingly so that begin/end stay balanced: - In non-snapshot mode, stop() always closes the buffer (the buffer may have run out of space, and that accounting is done by the update), so a following start() opens a fresh one as before. - In snapshot/overwrite mode, stop() without PERF_EF_UPDATE leaves the buffer open so that pt_event_snapshot_aux() can still copy from it, and start() then only re-enables tracing instead of calling perf_aux_output_begin() again. Note that pt_event_del() calls pt_event_stop() with PERF_EF_UPDATE flag set (as is required by the documentation), so a final call to perf_aux_output_end() is assured.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 52ca9ced3f70779589e6ecc329baffe69d8f5f7a 9b919fb5512f256e9e0604faf960b2bb98aab454 git Not specified
CNA Linux Linux affected 52ca9ced3f70779589e6ecc329baffe69d8f5f7a cab5015ee3f25f789b4a368f2abfa65536576b78 git Not specified
CNA Linux Linux affected 52ca9ced3f70779589e6ecc329baffe69d8f5f7a 304844b5545f444d523286da8228a1cbc46ffffa git Not specified
CNA Linux Linux affected 52ca9ced3f70779589e6ecc329baffe69d8f5f7a 2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d git Not specified
CNA Linux Linux affected 4.1 Not specified
CNA Linux Linux unaffected 4.1 semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.52 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9b919fb5512f256e9e0604faf960b2bb98aab454 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cab5015ee3f25f789b4a368f2abfa65536576b78 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/304844b5545f444d523286da8228a1cbc46ffffa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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