CVE-2024-42223: Linux Kernel Media DVB-Frontends TDA10048 Integer Overflow Fix

In the world of cybersecurity, no software is completely safe from vulnerabilities, and the Linux kernel is no exception. In this post, we will discuss a vulnerability that was identified in the Linux kernel media subsystem and how it has been resolved. The vulnerability, assigned as CVE-2024-42223, relates to an integer overflow issue found within the media: dvb-frontends: tda10048 specific module.

This vulnerability could have an impact on systems running Linux kernels with affected modules enabled, and if exploited, might lead to various security issues and system crashes. Luckily, it has now been resolved, and we will cover the details of this fix. In this long read, we will provide code snippets to explain the vulnerability and the solution, along with further references to original sources and exploit details.

What is the CVE-2024-42223 vulnerability?

Within the Linux kernel, the media: dvb-frontends: tda10048 module is responsible for handling specific Digital Video Broadcasting (DVB) frontends. However, an integer overflow was discovered in this module, relating to the state->xtal_hz variable, which can hold a value of up to 16 million (16M).

The issue arises when this variable is multiplied by the pll_mfactor, causing an overflow of the 32-bit integer variable. This can lead to unwanted behavior and, in specific cases, may even allow attackers to exploit the system running the affected Linux kernel.

Fixing the integer overflow

To correct the CVE-2024-42223 vulnerability, a new 64-bit variable needs to be created to accommodate the calculations, ensuring that the 32-bit integer variable doesn't overflow. Here's a sample code snippet designed to illustrate the fix:

#include <linux/types.h>

/* ... Other declarations and code ... */

int64_t calculate_pll(uint32_t xtal_hz, uint32_t pll_mfactor)
{
    int64_t result;

    result = xtal_hz * (int64_t)pll_mfactor; // Use a 64-bit variable for the calculation

    /* ... Further calculations and code ... */

    return result;
}

In the code snippet above, the int64_t data type is used to create a new 64-bit variable called result. By utilizing this new variable in the calculation, the integer overflow can be safely avoided.

References and further reading

- Linux kernel Git commit for the integer overflow fix
- Official CVE information
- Media subsystem in the Linux kernel

Conclusion

The discovery and remediation of CVE-2024-42223 showcases the importance of being vigilant about identifying and addressing vulnerabilities in software, even those as reputable as the Linux kernel. By creating a new 64-bit variable to handle the large calculations involved, this issue has been resolved, ensuring that systems running the Linux kernel are even more secure.

Timeline

Published on: 07/30/2024 08:15:07 UTC
Last modified on: 08/02/2024 14:24:48 UTC