fkie_cve-2025-21899
Vulnerability from fkie_nvd
Published
2025-04-01 16:15
Modified
2025-10-31 18:51
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.14 | |
| linux | linux_kernel | 6.14 | |
| linux | linux_kernel | 6.14 | |
| linux | linux_kernel | 6.14 |
{
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"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": "2025-10-31T18:51:10.537",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2025-04-01T16:15:20.327",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/435d2964af815aae456db554c62963b4515f19d0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-476"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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