fkie_cve-2025-21899
Vulnerability from fkie_nvd
Published
2025-04-01 16:15
Modified
2025-04-01 20:26
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix bad hist from corrupting named_triggers list The following commands causes a crash: ~# cd /sys/kernel/tracing/events/rcu/rcu_callback ~# echo 'hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)' > trigger bash: echo: write error: Invalid argument ~# echo 'hist:name=bad:keys=common_pid' > trigger Because the following occurs: event_trigger_write() { trigger_process_regex() { event_hist_trigger_parse() { data = event_trigger_alloc(..); event_trigger_register(.., data) { cmd_ops->reg(.., data, ..) [hist_register_trigger()] { data->ops->init() [event_hist_trigger_init()] { save_named_trigger(name, data) { list_add(&data->named_list, &named_triggers); } } } } ret = create_actions(); (return -EINVAL) if (ret) goto out_unreg; [..] ret = hist_trigger_enable(data, ...) { list_add_tail_rcu(&data->list, &file->triggers); <<<---- SKIPPED!!! (this is important!) [..] out_unreg: event_hist_unregister(.., data) { cmd_ops->unreg(.., data, ..) [hist_unregister_trigger()] { list_for_each_entry(iter, &file->triggers, list) { if (!hist_trigger_match(data, iter, named_data, false)) <- never matches continue; [..] test = iter; } if (test && test->ops->free) <<<-- test is NULL test->ops->free(test) [event_hist_trigger_free()] { [..] if (data->name) del_named_trigger(data) { list_del(&data->named_list); <<<<-- NEVER gets removed! } } } } [..] kfree(data); <<<-- frees item but it is still on list The next time a hist with name is registered, it causes an u-a-f bug and the kernel can crash. Move the code around such that if event_trigger_register() succeeds, the next thing called is hist_trigger_enable() which adds it to the list. A bunch of actions is called if get_named_trigger_data() returns false. But that doesn't need to be called after event_trigger_register(), so it can be moved up, allowing event_trigger_register() to be called just before hist_trigger_enable() keeping them together and allowing the file->triggers to be properly populated.
Impacted products
Vendor Product Version



{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix bad hist from corrupting named_triggers list\n\nThe following commands causes a crash:\n\n ~# cd /sys/kernel/tracing/events/rcu/rcu_callback\n ~# echo \u0027hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)\u0027 \u003e trigger\n bash: echo: write error: Invalid argument\n ~# echo \u0027hist:name=bad:keys=common_pid\u0027 \u003e trigger\n\nBecause the following occurs:\n\nevent_trigger_write() {\n  trigger_process_regex() {\n    event_hist_trigger_parse() {\n\n      data = event_trigger_alloc(..);\n\n      event_trigger_register(.., data) {\n        cmd_ops-\u003ereg(.., data, ..) [hist_register_trigger()] {\n          data-\u003eops-\u003einit() [event_hist_trigger_init()] {\n            save_named_trigger(name, data) {\n              list_add(\u0026data-\u003enamed_list, \u0026named_triggers);\n            }\n          }\n        }\n      }\n\n      ret = create_actions(); (return -EINVAL)\n      if (ret)\n        goto out_unreg;\n[..]\n      ret = hist_trigger_enable(data, ...) {\n        list_add_tail_rcu(\u0026data-\u003elist, \u0026file-\u003etriggers); \u003c\u003c\u003c---- SKIPPED!!! (this is important!)\n[..]\n out_unreg:\n      event_hist_unregister(.., data) {\n        cmd_ops-\u003eunreg(.., data, ..) [hist_unregister_trigger()] {\n          list_for_each_entry(iter, \u0026file-\u003etriggers, list) {\n            if (!hist_trigger_match(data, iter, named_data, false))   \u003c- never matches\n                continue;\n            [..]\n            test = iter;\n          }\n          if (test \u0026\u0026 test-\u003eops-\u003efree) \u003c\u003c\u003c-- test is NULL\n\n            test-\u003eops-\u003efree(test) [event_hist_trigger_free()] {\n              [..]\n              if (data-\u003ename)\n                del_named_trigger(data) {\n                  list_del(\u0026data-\u003enamed_list);  \u003c\u003c\u003c\u003c-- NEVER gets removed!\n                }\n              }\n           }\n         }\n\n         [..]\n         kfree(data); \u003c\u003c\u003c-- frees item but it is still on list\n\nThe next time a hist with name is registered, it causes an u-a-f bug and\nthe kernel can crash.\n\nMove the code around such that if event_trigger_register() succeeds, the\nnext thing called is hist_trigger_enable() which adds it to the list.\n\nA bunch of actions is called if get_named_trigger_data() returns false.\nBut that doesn\u0027t need to be called after event_trigger_register(), so it\ncan be moved up, allowing event_trigger_register() to be called just\nbefore hist_trigger_enable() keeping them together and allowing the\nfile-\u003etriggers to be properly populated."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tracing: Fix bad hist from corrupting named_triggers list Los siguientes comandos provocan un bloqueo: ~# cd /sys/kernel/tracing/events/rcu/rcu_callback ~# echo \u0027hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)\u0027 \u0026gt; trigger bash: echo: error de escritura: argumento no v\u00e1lido ~# echo \u0027hist:name=bad:keys=common_pid\u0027 \u0026gt; trigger Porque ocurre lo siguiente: event_trigger_write() { trigger_process_regex() { event_hist_trigger_parse() { data = event_trigger_alloc(..); event_trigger_register(.., data) { cmd_ops-\u0026gt;reg(.., data, ..) [hist_register_trigger()] { data-\u0026gt;ops-\u0026gt;init() [event_hist_trigger_init()] { save_named_trigger(name, data) { list_add(\u0026amp;data-\u0026gt;named_list, \u0026amp;named_triggers); } } } } ret = create_actions(); (return -EINVAL) if (ret) goto out_unreg; [..] ret = hist_trigger_enable(data, ...) { list_add_tail_rcu(\u0026amp;data-\u0026gt;list, \u0026amp;file-\u0026gt;triggers); \u0026lt;\u0026lt;\u0026lt;---- \u00a1\u00a1\u00a1SALTAR!!! (\u00a1esto es importante!) [..] out_unreg: event_hist_unregister(.., data) { cmd_ops-\u0026gt;unreg(.., data, ..) [hist_unregister_trigger()] { list_for_each_entry(iter, \u0026amp;file-\u0026gt;triggers, list) { if (!hist_trigger_match(data, iter, named_data, false)) \u0026lt;- never matches continue; [..] test = iter; } if (test \u0026amp;\u0026amp; test-\u0026gt;ops-\u0026gt;free) \u0026lt;\u0026lt;\u0026lt;-- test is NULL test-\u0026gt;ops-\u0026gt;free(test) [event_hist_trigger_free()] { [..] if (data-\u0026gt;name) del_named_trigger(data) { list_del(\u0026amp;data-\u0026gt;named_list); \u0026lt;\u0026lt;\u0026lt;\u0026lt;-- \u00a1NUNCA se elimina! } } } } [..] kfree(datos); \u0026lt;\u0026lt;\u0026lt;-- libera el elemento, pero sigue en la lista. La pr\u00f3xima vez que se registre un hist con nombre, se producir\u00e1 un error de uaf y el kernel podr\u00eda bloquearse. Desplace el c\u00f3digo de forma que, si event_trigger_register() tiene \u00e9xito, se llame a hist_trigger_enable(), lo que lo a\u00f1ade a la lista. Se invocan varias acciones si get_named_trigger_data() devuelve falso. Sin embargo, no es necesario llamarlo despu\u00e9s de event_trigger_register(), por lo que se puede adelantar, lo que permite llamar a event_trigger_register() justo antes de hist_trigger_enable(), manteni\u00e9ndolos juntos y permitiendo que los disparadores de archivo se rellenen correctamente."
    }
  ],
  "id": "CVE-2025-21899",
  "lastModified": "2025-04-01T20:26:01.990",
  "metrics": {},
  "published": "2025-04-01T16:15:20.327",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/435d2964af815aae456db554c62963b4515f19d0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/43b254d46c740bf9dbe65709afa021dd726dfa99"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5ae1b18f05ee2b849dc03b6c15d7da0c1c6efa77"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f1ae50cfb818ce1ac7a674406dfadb7653e2552d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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