Overview: A vulnerability in the Linux kernel has been identified and resolved, affecting the wifi driver module known as rtl8xxxu. This vulnerability - CVE-2024-27052 - could have led to use-after-free issues causing undesired system behavior. This blog post will discuss the details of the vulnerability, the code changes that have been made, links to original references, and exploit details.

Vulnerability Details

The wifi driver in question, rtl8xxxu, had an issue in which the work queue may still be running when the driver is stopped. This could lead to a situation where memory allocated to the work queue is no longer valid and thus lead to a use-after-free problem. To prevent this from occurring, developers have added a call to cancel_work_sync() in the rtl8xxxu_stop() function.

A use-after-free vulnerability happens when a pointer still points to a memory location that has been freed, typically due to a bug in the program's memory management process. The result can be unpredictable, as another process might reallocate that memory space and overwrite its contents, leading to possible data corruption or even control flow hijacking.

To address this vulnerability, the following changes were made to the rtl8xxxu kernel module

static void rtl8xxxu_stop(struct ieee80211_hw *hw)
{
    ...
+   cancel_work_sync(&priv->c2hcmd_work);
    ...
}

The addition of cancel_work_sync(&priv->c2hcmd_work); ensures that any ongoing work in the work queue is properly stopped and cleaned up before the driver is halted, mitigating the potential use-after-free scenario.

References

- Original vulnerability report: Link to the vulnerability report
- Linux kernel patch: Link to the kernel patch

Exploit Details

While the presence of a use-after-free vulnerability increases the potential attack surface, the specific conditions required to exploit this scenario in the wifi driver context may be difficult to achieve. Still, it is essential to ensure that kernel code is as secure and robust as possible, especially considering the potential increase in vulnerabilities when combined with other driver or kernel flaws.

Wrapping Up

CVE-2024-27052 exposes a vulnerability in the Linux kernel, specifically in the rtl8xxxu wifi driver. By adding a call to cancel_work_sync() in the rtl8xxxu_stop() function, developers have successfully mitigated this potential use-after-free situation. It is always advisable to stay up-to-date with the latest kernel patches and security fixes to ensure the continued safety and stability of your systems.

Timeline

Published on: 05/01/2024 13:15:50 UTC
Last modified on: 07/03/2024 01:50:17 UTC