A recently resolved vulnerability has been identified in the Linux kernel, specifically affecting the Advanced Linux Sound Architecture (ALSA) System on Chip (ASoC) Sound Open Firmware (SOF) component. The vulnerability, assigned CVE-2024-26927, can trigger an issue related to bounds checking in firmware data, causing a potential underflow.

Description

The Linux kernel vulnerability, CVE-2024-26927, became apparent when Smatch, a source code checker tool, warned about a potential underflow in the expression "head->full_size - head->header_size" within the ASoC SOF component. While firmware is generally expected to be somewhat trustworthy, this vulnerability highlights the need for proper bounds checking to minimize potential risks.

To address this issue, the Linux kernel maintainers added a check not only for negative values that could cause an underflow but also an upper bounds check for added safety.

Here is the patched code snippet that addresses the bounds checking vulnerability

if ((head->full_size - head->header_size) <=  || (head->full_size - head->header_size) > SOF_FW_MAX_SIZE) {
    dev_err(dev, "error: invalid header_size\n");
    return -EINVAL;
}

This new code ensures that the difference between "head->full_size" and "head->header_size" is not negative, and also checks if it exceeds the constant "SOF_FW_MAX_SIZE", which provides an upper bounds limit.

1. Linux kernel mailing list - Patch submission: ASoC: SOF: Add some bounds checking to firmware data
2. Smatch - A source code checker tool: http://repo.or.cz/w/smatch.git

Exploit Details

As this vulnerability is related to bounds checking and potential underflow, an attacker could potentially exploit this by crafting malicious firmware that causes unexpected behavior in the ASoC SOF component. The negative value check and upper bounds limit introduced in the patch significantly reduce this risk.

Conclusion

The Linux kernel maintainers have resolved the bounds checking vulnerability (CVE-2024-26927) within the ASoC SOF component. The added negative value check and upper bounds limit enhance the overall security and robustness of the Linux kernel, safeguarding against potential underflow attacks that could exploit this vulnerability. Users and organizations utilizing the ASoC SOF component in their Linux kernel are advised to update their systems to the latest version, which includes the patch for this vulnerability.

Timeline

Published on: 04/28/2024 12:15:21 UTC
Last modified on: 08/02/2024 00:21:05 UTC