GHSA-VP9F-G82M-H958
Vulnerability from github – Published: 2025-04-01 18:30 – Updated: 2025-11-03 21:33In 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.
{
"affected": [],
"aliases": [
"CVE-2025-21899"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-01T16:15:20Z",
"severity": "MODERATE"
},
"details": "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.",
"id": "GHSA-vp9f-g82m-h958",
"modified": "2025-11-03T21:33:20Z",
"published": "2025-04-01T18:30:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21899"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/435d2964af815aae456db554c62963b4515f19d0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/43b254d46c740bf9dbe65709afa021dd726dfa99"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5ae1b18f05ee2b849dc03b6c15d7da0c1c6efa77"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f1ae50cfb818ce1ac7a674406dfadb7653e2552d"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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