{"id":"CVE-2026-99234","published":"2026-11-02T16:17:48.597","lastModified":"2026-11-02T16:17:48.597","description":"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->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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/431959fc76456cbba539279fe8967aa9391e6f23","tags":[]},{"url":"https://git.kernel.org/stable/c/5afb9317e2eeb1c7021a82995ce244fda5a4bd4f","tags":[]},{"url":"https://git.kernel.org/stable/c/8482ec5b65f606d5bbcec518e0afc69ad65ca414","tags":[]},{"url":"https://git.kernel.org/stable/c/a3d7ffd2409700748a495b645948fef48199206e","tags":[]},{"url":"https://git.kernel.org/stable/c/aae0ccd7326eef78dcdefffef3d1253e6f0615ca","tags":[]},{"url":"https://git.kernel.org/stable/c/d0090baf02dd08f6e909f36f0ad54a4e80f5e79b","tags":[]},{"url":"https://git.kernel.org/stable/c/dba0f492703956801149cc70b39d2650a37995c3","tags":[]},{"url":"https://git.kernel.org/stable/c/f21351d1c4cdcc6a68f03636a407c2af1a5e1e10","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}