{"id":"CVE-2026-99234","summary":"tracing: Unregister field variable histograms when the command fails","details":"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_hist() registers a second hist trigger on\nthat event to provide it, and records it in\ntarget_hist_data-\u003efield_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' \u003e\u003e \\\n      events/sched/sched_waking/trigger\n  # echo 'my_synth u64 lat; int a; int b' \u003e\u003e 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      \u003e\u003e 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.","modified":"2026-11-10T17:27:01.222848641Z","published":"2026-11-02T16:06:41.083Z","related":["openSUSE-SU-2026:12497-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99234.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/431959fc76456cbba539279fe8967aa9391e6f23"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5afb9317e2eeb1c7021a82995ce244fda5a4bd4f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8482ec5b65f606d5bbcec518e0afc69ad65ca414"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91c14d6c13096091c56304120aaa26e479130b8b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a3d7ffd2409700748a495b645948fef48199206e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aae0ccd7326eef78dcdefffef3d1253e6f0615ca"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d0090baf02dd08f6e909f36f0ad54a4e80f5e79b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dba0f492703956801149cc70b39d2650a37995c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f21351d1c4cdcc6a68f03636a407c2af1a5e1e10"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99234.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99234"},{"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":"02205a6752f223779a1b0e9e8ffacbea6e717851"},{"fixed":"f21351d1c4cdcc6a68f03636a407c2af1a5e1e10"},{"fixed":"dba0f492703956801149cc70b39d2650a37995c3"},{"fixed":"a3d7ffd2409700748a495b645948fef48199206e"},{"fixed":"aae0ccd7326eef78dcdefffef3d1253e6f0615ca"},{"fixed":"8482ec5b65f606d5bbcec518e0afc69ad65ca414"},{"fixed":"431959fc76456cbba539279fe8967aa9391e6f23"},{"fixed":"5afb9317e2eeb1c7021a82995ce244fda5a4bd4f"},{"fixed":"d0090baf02dd08f6e909f36f0ad54a4e80f5e79b"},{"fixed":"91c14d6c13096091c56304120aaa26e479130b8b"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99234.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.17.0"},{"fixed":"5.10.273"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.224"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.161"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.115"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.60"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.3.0"},{"fixed":"7.3.1"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-99234.json"}}],"schema_version":"1.9.2"}