GHSA-F4G2-C45M-RQ74
Vulnerability from github – Published: 2024-12-27 15:31 – Updated: 2025-10-08 15:32In the Linux kernel, the following vulnerability has been resolved:
net/l2tp: fix warning in l2tp_exit_net found by syzbot
In l2tp's net exit handler, we check that an IDR is empty before destroying it:
WARN_ON_ONCE(!idr_is_empty(&pn->l2tp_tunnel_idr));
idr_destroy(&pn->l2tp_tunnel_idr);
By forcing memory allocation failures in idr_alloc_32, syzbot is able to provoke a condition where idr_is_empty returns false despite there being no items in the IDR. This turns out to be because the radix tree of the IDR contains only internal radix-tree nodes and it is this that causes idr_is_empty to return false. The internal nodes are cleaned by idr_destroy.
Use idr_for_each to check that the IDR is empty instead of idr_is_empty to avoid the problem.
{
"affected": [],
"aliases": [
"CVE-2024-53211"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-27T14:15:29Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/l2tp: fix warning in l2tp_exit_net found by syzbot\n\nIn l2tp\u0027s net exit handler, we check that an IDR is empty before\ndestroying it:\n\n\tWARN_ON_ONCE(!idr_is_empty(\u0026pn-\u003el2tp_tunnel_idr));\n\tidr_destroy(\u0026pn-\u003el2tp_tunnel_idr);\n\nBy forcing memory allocation failures in idr_alloc_32, syzbot is able\nto provoke a condition where idr_is_empty returns false despite there\nbeing no items in the IDR. This turns out to be because the radix tree\nof the IDR contains only internal radix-tree nodes and it is this that\ncauses idr_is_empty to return false. The internal nodes are cleaned by\nidr_destroy.\n\nUse idr_for_each to check that the IDR is empty instead of\nidr_is_empty to avoid the problem.",
"id": "GHSA-f4g2-c45m-rq74",
"modified": "2025-10-08T15:32:25Z",
"published": "2024-12-27T15:31:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-53211"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5d066766c5f1252f98ff859265bcd1a5b52ac46c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a487cc8986d6dd75b60b59004f3bd2ea9b4dd541"
}
],
"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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