CVE-2026-93275

Full vulnerability record from the local CVENow database.

Description

In 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.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-24 16:17:24.667000

Last modified

2026-10-19 10:17:19.020000

View original CVE JSON

{
  "id": "CVE-2026-93275",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-24T16:17:24.667",
  "lastModified": "2026-10-19T10:17:19.020",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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 ->stop() / ->start() callbacks without flags.\n\nAn example is when AUX area sampling is used. The following commands\nhit the issue:\n\n  echo 10000 > /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."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "arch/x86/events/intel/pt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "9734e25fbf5ae68eb04234b2cd14a4b36ab89141",
              "lessThan": "cab5015ee3f25f789b4a368f2abfa65536576b78",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9734e25fbf5ae68eb04234b2cd14a4b36ab89141",
              "lessThan": "304844b5545f444d523286da8228a1cbc46ffffa",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9734e25fbf5ae68eb04234b2cd14a4b36ab89141",
              "lessThan": "2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "arch/x86/events/intel/pt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6.16",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.16",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.52",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.6",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2e17bf3a469a41457a3bc31b1f8fd66b6ce94a6d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/304844b5545f444d523286da8228a1cbc46ffffa",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/cab5015ee3f25f789b4a368f2abfa65536576b78",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}