CVE-2024-42089: Linux Kernel Vulnerability Resolved in ASoC: fsl-asoc-card

In the Linux kernel, a vulnerability has been identified and resolved, as detailed in the official CVE listing under CVE-2024-42089. This vulnerability is related to the Advanced Linux Sound Architecture (ALSA) System on Chip (ASoC) subsystem, specifically the fsl-asoc-card driver. In this post, we'll explore the details of this vulnerability, provide a code snippet illustrating the issue, and include links to original references and additional information.

Overview

The Linux kernel's ASoC subsystem is responsible for managing and enabling audio devices and codecs on embedded systems. The fsl-asoc-card driver provides support for audio devices on Freescale platforms. The vulnerability identified in this driver involves incorrect handling of the priv->pdev pointer within the fsl_asoc_card_audmux_init() function.

The Vulnerability

In the Linux kernel commit 9edbf298fb92, the issue is described as follows:

> priv->pdev pointer was set after being used in fsl_asoc_card_audmux_init().
Move this assignment at the start of the probe function, so
sub-functions can correctly use pdev through priv.

The vulnerability can result in a NULL pointer dereference, which could lead to a system crash or undefined behavior. However, the issue can escape detection and not cause an immediate crash in some cases, due to compiler optimizations.

Code Snippet

The fix for this vulnerability is relatively simple and involves moving the assignment of the priv->pdev pointer earlier in the probe function. Here's a snippet of the code illustrating the change:

// Before
static int fsl_asoc_card_probe(struct platform_device *pdev) {
  ...
  ret = fsl_asoc_card_audmux_init(priv);
  if (ret)
    return ret;
  
  priv->pdev = pdev;
  ...
}

// After
static int fsl_asoc_card_probe(struct platform_device *pdev) {
  ...
  priv->pdev = pdev;
  
  ret = fsl_asoc_card_audmux_init(priv);
  if (ret)
    return ret;
  ...
}

As can be seen from the code snippet above, the assignment of priv->pdev = pdev; has been moved before the call to fsl_asoc_card_audmux_init(priv);.

Exploit Details

As this vulnerability involves a NULL pointer dereference, it does not provide a direct attack vector for malicious actions. However, it is important to patch and address the issue to ensure system stability and avoid crashes caused by incorrect handling of the priv->pdev pointer within the fsl-asoc-card driver.

Original References and Additional Information

The Linux kernel commit addressing this vulnerability is available on the git.kernel.org website: 9edbf298fb92

For further information about the Linux kernel and ASoC subsystem, you might want to refer to the official Linux kernel documentation: Linux ASoC framework documentation and ALSA project website

In conclusion, the CVE-2024-42089 vulnerability identified and resolved in the Linux kernel's fsl-asoc-card driver highlights the importance of proper pointer handling and code structure. Regularly updating and patching the Linux kernel is essential to maintain system integrity and prevent associated issues.

Timeline

Published on: 07/29/2024 17:15:11 UTC
Last modified on: 07/30/2024 13:33:30 UTC