{"id":"CVE-2026-89746","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89746","summary":"tracing: Fix use-after-free with same-name named triggers","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix use-after-free with same-name named triggers\n\nWhen two hist triggers on different events are registered with the same\nname=, the second one reuses the first as named_data.  Both are added to\ntr->hist_vars by save_hist_vars() during event_hist_trigger_parse(),\nbecause save_hist_vars() is called before event_trigger_register() while\nthe named reuse is only detected later, in hist_register_trigger().\n\nIn the named-data branch hist_register_trigger() then frees the second\nhistogram's hist_data via destroy_hist_data(), but never removes its\ntr->hist_vars list entry, leaving a dangling pointer and leaking the\ntrace_array reference it holds.\n\nA later hist trigger that references a variable makes find_var_file()\nwalk tr->hist_vars and dereference the freed hist_data.  The bug is\nreproducible from userspace by writing three hist triggers to tracefs:\n\n  cd /sys/kernel/tracing\n  echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_switch/trigger\n  echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_process_fork/trigger\n  echo 'hist:keys=common_pid:vals=$x' > events/sched/sched_process_exit/trigger\n\nThe third write panics the kernel:\n\n  BUG: KASAN: slab-use-after-free in find_var_file.part.0+0x272/0x290\n  Read of size 8 at addr ffff888001f8a0e0 by task sh/1\n  CPU: 1 UID: 0 PID: 1 Comm: sh Tainted: G      D          N\n  Call Trace:\n    find_var_file.part.0\n    find_event_var\n    parse_atom\n    parse_expr\n    __create_val_field\n    event_hist_trigger_parse\n    trigger_process_regex\n    event_trigger_write\n    vfs_write\n    ksys_write\n    do_syscall_64\n    entry_SYSCALL_64_after_hwframe\n  Allocated by task 1:\n    event_hist_trigger_parse\n  Freed by task 1:\n    hist_register_trigger+0x618/0xa30\n    event_hist_trigger_parse\n  The buggy address belongs to freed 2048-byte region\n  Oops: general protection fault ... RIP: find_var_file.part.0\n  Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b\n\nFix by removing the hist_data from tr->hist_vars and releasing the\ntrace_array reference in the named-data branch of hist_register_trigger()\nbefore freeing the hist_data.","published":"2026-09-11T19:46:51.529Z","modified":"2026-09-14T03:46:33.950837054Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/477d762be4b0ffaf01429ccd88859e93b0ec28cc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/83d1ae0406d8eade219a81b401e201702dd9dc55"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a7318172aa332a161fb9618286e64454c827f8fd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b1a49c22de01faf176d44e5caa765e237353a579"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89746.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89746"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:33.950837054Z"}}