cve/2024/CVE-2024-53211.md

### [CVE-2024-53211](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-53211)
![](https://img.shields.io/static/v1?label=Product&message=Linux&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=73d33bd063c4cfef3db17f9bec3d202928ed8631%3C%20a487cc8986d6dd75b60b59004f3bd2ea9b4dd541%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brighgreen)

### Description

In the Linux kernel, the following vulnerability has been resolved:net/l2tp: fix warning in l2tp_exit_net found by syzbotIn l2tp's net exit handler, we check that an IDR is empty beforedestroying 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 ableto provoke a condition where idr_is_empty returns false despite therebeing no items in the IDR. This turns out to be because the radix treeof the IDR contains only internal radix-tree nodes and it is this thatcauses idr_is_empty to return false. The internal nodes are cleaned byidr_destroy.Use idr_for_each to check that the IDR is empty instead ofidr_is_empty to avoid the problem.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/cku-heise/euvd-api-doc