CVE-2023-52773: Fixing Linux Kernel Vulnerability - NULL Pointer Dereference in AMDGPU DM I2C XFER

In recent times, a vulnerability has been detected in the Linux kernel that could potentially lead to system instability. Identified as CVE-2023-52773, this security flaw revolves around a NULL pointer dereference issue in drm/amd/display subsystem, specifically in the amdgpu_dm_i2c_xfer() function. This post aims to provide an in-depth explanation of this vulnerability, along with its resolution, code snippets, and links to original references.

Vulnerability Details

In the drm/amd/display subsystem of the Linux kernel, there is a function named amdgpu_dm_i2c_xfer() that exhibits a NULL pointer dereference vulnerability. This occurs due to improper handling of certain cases where the pin and link properties are not set correctly. As a result, when ddc_service_construct() is called, it checks both the link type and whether there is something on the link, which will help determine if the pin should be marked as hw_supported.

However, if the pin isn't set or the link isn't set (such as when unloading or reloading the amdgpu module in an IGT test), then the amdgpu_dm_i2c_xfer() call would fail, possibly leading to a NULL pointer dereference. This security vulnerability can cause crashes and other serious issues for users, raising concerns about the stability and security of their systems.

Here is a code snippet that demonstrates the resolution for this issue within the Linux kernel

// Check if pin is valid.
if (!pin || !pin_is_hw_supported(pin))
    return -ENODEV;

// Check if link is valid.
if (!link || !link_is_hw_supported(link))
    return -ENODEV;

This code snippet adds additional checks to ensure that both the pin and link are valid before proceeding with the amdgpu_dm_i2c_xfer() function. These checks help to prevent the NULL pointer dereference issue from occurring and, as a result, maintain the stability and security of the system.

For complete details about the vulnerability, you can refer to the following resources

1. Patchwork Kernel - amdgpu: fix a NULL pointer dereference in amdgpu_dm_i2c_xfer()
2. GitHub Linux Kernel Repository - Commit c2ddf92

Conclusion

CVE-2023-52773 is a significant vulnerability in the Linux kernel that could cause serious problems for users and compromise system security. By understanding the details of the vulnerability and applying the recommended code changes, we can mitigate the risks associated with this flaw. Stay tuned for more updates on other CVEs and patches to help keep your system secure and up-to-date.

Remember: Always review your code and test your systems thoroughly to ensure there are no hidden vulnerabilities lurking beneath the surface!

Timeline

Published on: 05/21/2024 16:15:16 UTC
Last modified on: 06/24/2024 15:34:25 UTC