ghsa-hvr4-ppmm-c7fp
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net_sched: hfsc: Fix a UAF vulnerability in class handling
This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class handling. The issue occurs due to a time-of-check/time-of-use condition in hfsc_change_class() when working with certain child qdiscs like netem or codel.
The vulnerability works as follows: 1. hfsc_change_class() checks if a class has packets (q.qlen != 0) 2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g., codel, netem) might drop packets and empty the queue 3. The code continues assuming the queue is still non-empty, adding the class to vttree 4. This breaks HFSC scheduler assumptions that only non-empty classes are in vttree 5. Later, when the class is destroyed, this can lead to a Use-After-Free
The fix adds a second queue length check after qdisc_peek_len() to verify the queue wasn't emptied.
{
"affected": [],
"aliases": [
"CVE-2025-37797"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-02T15:15:48Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class handling\n\nThis patch fixes a Use-After-Free vulnerability in the HFSC qdisc class\nhandling. The issue occurs due to a time-of-check/time-of-use condition\nin hfsc_change_class() when working with certain child qdiscs like netem\nor codel.\n\nThe vulnerability works as follows:\n1. hfsc_change_class() checks if a class has packets (q.qlen != 0)\n2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g.,\n codel, netem) might drop packets and empty the queue\n3. The code continues assuming the queue is still non-empty, adding\n the class to vttree\n4. This breaks HFSC scheduler assumptions that only non-empty classes\n are in vttree\n5. Later, when the class is destroyed, this can lead to a Use-After-Free\n\nThe fix adds a second queue length check after qdisc_peek_len() to verify\nthe queue wasn\u0027t emptied.",
"id": "GHSA-hvr4-ppmm-c7fp",
"modified": "2025-05-02T15:31:48Z",
"published": "2025-05-02T15:31:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37797"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/28b09a067831f7317c3841812276022d6c940677"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283"
}
],
"schema_version": "1.4.0",
"severity": []
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- 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.