CVE-2023-53020: l2tp: close all race conditions in l2tp_tunnel_register()
First published: Thu Mar 27 2025(Updated: )
In the Linux kernel, the following vulnerability has been resolved: l2tp: close all race conditions in l2tp_tunnel_register() The code in l2tp_tunnel_register() is racy in several ways: 1. It modifies the tunnel socket _after_ publishing it. 2. It calls setup_udp_tunnel_sock() on an existing socket without locking. 3. It changes sock lock class on fly, which triggers many syzbot reports. This patch amends all of them by moving socket initialization code before publishing and under sock lock. As suggested by Jakub, the l2tp lockdep class is not necessary as we can just switch to bh_lock_sock_nested().
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2023-53020?
CVE-2023-53020 has been assessed to have a medium severity due to race conditions in l2tp_tunnel_register() affecting the Linux kernel.
How do I fix CVE-2023-53020?
To fix CVE-2023-53020, update your Linux kernel to the latest version that includes the patch resolving this vulnerability.
What systems are affected by CVE-2023-53020?
CVE-2023-53020 affects the Linux kernel, specifically instances that use the l2tp module.
When was CVE-2023-53020 published?
CVE-2023-53020 was published in 2023 as part of ongoing security improvements to the Linux kernel.
What are the implications of CVE-2023-53020?
The implications of CVE-2023-53020 include potential denial of service or instability in systems utilizing L2TP tunnels if the vulnerability is exploited.
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