Vulnerability-Lookup

GHSA-JPCJ-Q7F6-FXVJ

Vulnerability from github – Published: 2026-10-28 12:31 – Updated: 2026-10-28 12:31

Details

In the Linux kernel, the following vulnerability has been resolved:

tracing: Fix hist trigger timestamps for buffered events

Syzkaller triggered a WARN_ON_ONCE(!nest) warning:

WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp Call trace: ring_buffer_event_time_stamp hist_field_timestamp hist_fn_call event_hist_trigger event_triggers_call __event_trigger_test_discard trace_event_buffer_commit do_trace_event_raw_event_sched_switch trace_event_raw_event_sched_switch

The warning is probabilistically reproducible and is related to syzkaller executing the following commands:

echo 'prev_pid == 999999' > events/sched/sched_switch/filter echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger

The specific triggering process is as follows:

CPU 0 CPU 1 (context switching) (echo 'hist:keys=common_timestamp' > \ events/sched/sched_switch/trigger) do_trace_event_raw_event_##call trace_event_buffer_lock_reserve if (!tr->no_filter_buffering_ref && trace_file->flags & EVENT_FILE_FL_FILTERED) return entry; // return directly event_hist_trigger_parse hist_register_trigger tracing_set_filter_buffering(file->tr, true); tr->no_filter_buffering_ref++; __trace_buffer_lock_reserve rb_start_commit local_inc(&cpu_buffer->committing); // skipped and not executed trace_event_buffer_commit __event_trigger_test_discard event_triggers_call event_hist_trigger hist_fn_call hist_field_timestamp ring_buffer_event_time_stamp nest = local_read(&cpu_buffer->committing); WARN_ON_ONCE(!nest) // trigger warning

The root cause is that when an event file has a filter attached and the hist trigger has not yet been attached, trace_event_buffer_lock_reserve() writes the event into the per-CPU trace_buffered_event temp buffer instead of reserving it in the ring buffer, so cpu_buffer->committing is not incremented. When the event is later processed at commit time by a hist trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a zero committing count, triggering WARN_ON_ONCE(!nest).

tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing: Add tracing_event_time_stamp() API") for exactly this case: if the event is the per-CPU trace_buffered_event, it returns the current ring buffer timestamp. But it never gained a caller. Use it in hist_field_timestamp(), so that a hist trigger that races onto a buffered event records the current time, which is only marginally later than when the event was recorded, instead of warning and recording a bogus timestamp.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-99140"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-28T11:17:33Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo \u0027prev_pid == 999999\u0027 \u003e events/sched/sched_switch/filter\n  echo \u0027hist:keys=common_timestamp\u0027 \u003e events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo \u0027hist:keys=common_timestamp\u0027 \u003e \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr-\u003eno_filter_buffering_ref \u0026\u0026\n        trace_file-\u003eflags \u0026 EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file-\u003etr, true);\n                                                      tr-\u003eno_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(\u0026cpu_buffer-\u003ecommitting);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(\u0026cpu_buffer-\u003ecommitting);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer-\u003ecommitting is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -\u003e ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp.",
  "id": "GHSA-jpcj-q7f6-fxvj",
  "modified": "2026-10-28T12:31:04Z",
  "published": "2026-10-28T12:31:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99140"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09c7cce2e59e6b3b1807520bcb1980c561f15d1e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-99140 (GCVE-0-2026-99140)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34

Title

tracing: Fix hist trigger timestamps for buffered events

Summary

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix hist trigger timestamps for buffered events Syzkaller triggered a WARN_ON_ONCE(!nest) warning: WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp Call trace: ring_buffer_event_time_stamp hist_field_timestamp hist_fn_call event_hist_trigger event_triggers_call __event_trigger_test_discard trace_event_buffer_commit do_trace_event_raw_event_sched_switch trace_event_raw_event_sched_switch The warning is probabilistically reproducible and is related to syzkaller executing the following commands: echo 'prev_pid == 999999' > events/sched/sched_switch/filter echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger The specific triggering process is as follows: CPU 0 CPU 1 (context switching) (echo 'hist:keys=common_timestamp' > \ events/sched/sched_switch/trigger) do_trace_event_raw_event_##call trace_event_buffer_lock_reserve if (!tr->no_filter_buffering_ref && trace_file->flags & EVENT_FILE_FL_FILTERED) return entry; // return directly event_hist_trigger_parse hist_register_trigger tracing_set_filter_buffering(file->tr, true); tr->no_filter_buffering_ref++; __trace_buffer_lock_reserve rb_start_commit local_inc(&cpu_buffer->committing); // skipped and not executed trace_event_buffer_commit __event_trigger_test_discard event_triggers_call event_hist_trigger hist_fn_call hist_field_timestamp ring_buffer_event_time_stamp nest = local_read(&cpu_buffer->committing); WARN_ON_ONCE(!nest) // trigger warning The root cause is that when an event file has a filter attached and the hist trigger has not yet been attached, trace_event_buffer_lock_reserve() writes the event into the per-CPU trace_buffered_event temp buffer instead of reserving it in the ring buffer, so cpu_buffer->committing is not incremented. When the event is later processed at commit time by a hist trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a zero committing count, triggering WARN_ON_ONCE(!nest). tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing: Add tracing_event_time_stamp() API") for exactly this case: if the event is the per-CPU trace_buffered_event, it returns the current ring buffer timestamp. But it never gained a caller. Use it in hist_field_timestamp(), so that a hist trigger that races onto a buffered event records the current time, which is only marginally later than when the event was recorded, instead of warning and recording a bogus timestamp.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7033 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/09c7cce2e59e6b3b1…
https://git.kernel.org/stable/c/89e90b16aadd6e66b…
https://git.kernel.org/stable/c/9414ca3b99e5a7f1f…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: b94bc80df64823e676b506f8de7dcf6a688d681e , < 09c7cce2e59e6b3b1807520bcb1980c561f15d1e (git) Affected: b94bc80df64823e676b506f8de7dcf6a688d681e , < 89e90b16aadd6e66bd0323bc8dfc76a62e756b57 (git) Affected: b94bc80df64823e676b506f8de7dcf6a688d681e , < 9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0 (git)
Linux	Linux	Affected: 5.13 Unaffected: 0 , < 5.13 (semver) Unaffected: 6.18.59 , ≤ 6.18.* (semver) Unaffected: 7.2.13 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace_events_hist.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "09c7cce2e59e6b3b1807520bcb1980c561f15d1e",
              "status": "affected",
              "version": "b94bc80df64823e676b506f8de7dcf6a688d681e",
              "versionType": "git"
            },
            {
              "lessThan": "89e90b16aadd6e66bd0323bc8dfc76a62e756b57",
              "status": "affected",
              "version": "b94bc80df64823e676b506f8de7dcf6a688d681e",
              "versionType": "git"
            },
            {
              "lessThan": "9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0",
              "status": "affected",
              "version": "b94bc80df64823e676b506f8de7dcf6a688d681e",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace_events_hist.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.13"
            },
            {
              "lessThan": "5.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.59",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.13",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix hist trigger timestamps for buffered events\n\nSyzkaller triggered a WARN_ON_ONCE(!nest) warning:\n\n  WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp\n  Call trace:\n    ring_buffer_event_time_stamp\n    hist_field_timestamp\n    hist_fn_call\n    event_hist_trigger\n    event_triggers_call\n    __event_trigger_test_discard\n    trace_event_buffer_commit\n    do_trace_event_raw_event_sched_switch\n    trace_event_raw_event_sched_switch\n\nThe warning is probabilistically reproducible and is related to syzkaller\nexecuting the following commands:\n\n  echo \u0027prev_pid == 999999\u0027 \u003e events/sched/sched_switch/filter\n  echo \u0027hist:keys=common_timestamp\u0027 \u003e events/sched/sched_switch/trigger\n\nThe specific triggering process is as follows:\n\nCPU 0                                           CPU 1\n(context switching)                             (echo \u0027hist:keys=common_timestamp\u0027 \u003e \\\n                                                        events/sched/sched_switch/trigger)\ndo_trace_event_raw_event_##call\n  trace_event_buffer_lock_reserve\n    if (!tr-\u003eno_filter_buffering_ref \u0026\u0026\n        trace_file-\u003eflags \u0026 EVENT_FILE_FL_FILTERED)\n        return entry;  // return directly\n                                                event_hist_trigger_parse\n                                                  hist_register_trigger\n                                                    tracing_set_filter_buffering(file-\u003etr, true);\n                                                      tr-\u003eno_filter_buffering_ref++;\n    __trace_buffer_lock_reserve\n      rb_start_commit\n        local_inc(\u0026cpu_buffer-\u003ecommitting);  // skipped and not executed\n  trace_event_buffer_commit\n    __event_trigger_test_discard\n      event_triggers_call\n        event_hist_trigger\n          hist_fn_call\n            hist_field_timestamp\n              ring_buffer_event_time_stamp\n                nest = local_read(\u0026cpu_buffer-\u003ecommitting);\n                WARN_ON_ONCE(!nest)  // trigger warning\n\nThe root cause is that when an event file has a filter attached and the\nhist trigger has not yet been attached, trace_event_buffer_lock_reserve()\nwrites the event into the per-CPU trace_buffered_event temp buffer instead\nof reserving it in the ring buffer, so cpu_buffer-\u003ecommitting is not\nincremented. When the event is later processed at commit time by a hist\ntrigger, hist_field_timestamp() -\u003e ring_buffer_event_time_stamp() sees a\nzero committing count, triggering WARN_ON_ONCE(!nest).\n\ntracing_event_time_stamp() was added by commit d8279bfc5e959 (\"tracing:\nAdd tracing_event_time_stamp() API\") for exactly this case: if the event\nis the per-CPU trace_buffered_event, it returns the current ring buffer\ntimestamp. But it never gained a caller. Use it in hist_field_timestamp(),\nso that a hist trigger that races onto a buffered event records the\ncurrent time, which is only marginally later than when the event was\nrecorded, instead of warning and recording a bogus timestamp."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:51.421Z",
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          "url": "https://git.kernel.org/stable/c/89e90b16aadd6e66bd0323bc8dfc76a62e756b57"
        },
        {
          "url": "https://git.kernel.org/stable/c/9414ca3b99e5a7f1f3bf51c2a01b383e1b355dd0"
        }
      ],
      "title": "tracing: Fix hist trigger timestamps for buffered events",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
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    "cveId": "CVE-2026-99140",
    "datePublished": "2026-10-28T10:34:51.421Z",
    "dateReserved": "2026-09-25T10:25:14.395Z",
    "dateUpdated": "2026-10-28T10:34:51.421Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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