{"id":"CVE-2026-99234","title":"tracing: Unregister field variable histograms when the command fails","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Unregister field variable histograms when the command fails\n\nAn action that names a field on another event needs that field as a\nvariable, so create_field_var_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < f21351d1c4cdcc6a68f03636a407c2af1a5e1e10","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < dba0f492703956801149cc70b39d2650a37995c3","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < a3d7ffd2409700748a495b645948fef48199206e","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < aae0ccd7326eef78dcdefffef3d1253e6f0615ca","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 8482ec5b65f606d5bbcec518e0afc69ad65ca414","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 431959fc76456cbba539279fe8967aa9391e6f23","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 5afb9317e2eeb1c7021a82995ce244fda5a4bd4f","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < d0090baf02dd08f6e909f36f0ad54a4e80f5e79b","Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 91c14d6c13096091c56304120aaa26e479130b8b","Linux 4.17"],"published":"2026-11-02","updated":"2026-11-03","sourceUpdated":"2026-11-03T19:13:02.797Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99234","references":[{"url":"https://git.kernel.org/stable/c/f21351d1c4cdcc6a68f03636a407c2af1a5e1e10"},{"url":"https://git.kernel.org/stable/c/dba0f492703956801149cc70b39d2650a37995c3"},{"url":"https://git.kernel.org/stable/c/a3d7ffd2409700748a495b645948fef48199206e"},{"url":"https://git.kernel.org/stable/c/aae0ccd7326eef78dcdefffef3d1253e6f0615ca"},{"url":"https://git.kernel.org/stable/c/8482ec5b65f606d5bbcec518e0afc69ad65ca414"},{"url":"https://git.kernel.org/stable/c/431959fc76456cbba539279fe8967aa9391e6f23"},{"url":"https://git.kernel.org/stable/c/5afb9317e2eeb1c7021a82995ce244fda5a4bd4f"},{"url":"https://git.kernel.org/stable/c/d0090baf02dd08f6e909f36f0ad54a4e80f5e79b"},{"url":"https://git.kernel.org/stable/c/91c14d6c13096091c56304120aaa26e479130b8b"}],"tags":["cve.org"],"epss":0.00182,"epssPercentile":0.0786,"ingestedAt":"2026-11-05T20:33:06.386Z","slug":"CVE-2026-99234","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Unregister field variable histograms when the command fails\n\nAn action that names a field on another event needs that field as a\nvariable, so create_field_var_hist() registers a second hist trigger on\nthat event to provide it, and records it in\ntarget_hist_data->field_var_hists[].\n\nIf a later part of the same command fails, create_actions() returns an\nerror and event_hist_trigger_parse() jumps to out_free. The write fails\nwith -EINVAL and sched_switch gets no trigger, but:\n\n  # echo 'hist:keys=pid:ts0=common_timestamp.usecs' >> \\\n      events/sched/sched_waking/trigger\n  # echo 'my_synth u64 lat; int a; int b' >> synthetic_events\n  # echo 'hist:keys=next_pid:wakeup_lat=common_timestamp.usecs-$ts0:\\\n      onmatch(sched.sched_waking).my_synth($wakeup_lat,prio,nosuchfld)'\\\n      >> events/sched/sched_switch/trigger\n  # cat events/sched/sched_waking/trigger\n  hist:keys=pid:vals=hitcount:ts0=common_timestamp.usecs:sort=hitcount:size=2048:clock=global [active]\n  hist:keys=pid:vals=hitcount:synthetic_prio=prio:sort=hitcount:size=2048 [active]\n\nThe second histogram is the one created for 'prio'. It is still active and\nstill counting.\n\nout_free reaches destroy_field_var_hists(), which frees the\nfield_var_hists[] entries, but never unregister_field_var_hists(), which is\nwhat removes the triggers and runs only from event_hist_trigger_free(). The\nentry is freed and the trigger is left with nothing tracking it.\n\nUnregister the field variable histograms in out_free as well, and record\neach one as soon as its trigger is registered rather than after the lookup\nthat follows it, so no exit can leave a registered trigger untracked. The\nentry then belongs to field_var_hists[] and is released by\ndestroy_field_var_hists(), so freeing it on that exit would be a double\nfree.\n\n## Affected\n\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < f21351d1c4cdcc6a68f03636a407c2af1a5e1e10`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < dba0f492703956801149cc70b39d2650a37995c3`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < a3d7ffd2409700748a495b645948fef48199206e`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < aae0ccd7326eef78dcdefffef3d1253e6f0615ca`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 8482ec5b65f606d5bbcec518e0afc69ad65ca414`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 431959fc76456cbba539279fe8967aa9391e6f23`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 5afb9317e2eeb1c7021a82995ce244fda5a4bd4f`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < d0090baf02dd08f6e909f36f0ad54a4e80f5e79b`\n- `Linux >= 02205a6752f223779a1b0e9e8ffacbea6e717851 < 91c14d6c13096091c56304120aaa26e479130b8b`\n- `Linux 4.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}