CVE-2024-47754 - Linux Kernel Media Vulnerability Resolved: Mediatek Vcodec H264 Multi Stateless Decoder Smatch Warning Fix

A crucial vulnerability has been identified and resolved in the Linux kernel regarding the Mediatek Vcodec H264 multi stateless decoder. As per the Common Vulnerabilities and Exposures (CVE) system, this vulnerability receives the identification code CVE-2024-47754. In this article, we will analyze in detail the vulnerability, its related patch, and the context of the Linux kernel's media structure. Finally, we will explore the potential ramifications had this vulnerability not been addressed.

Vulnerability Details

The vulnerability in question revolves around the Linux kernel's media subsystem, specifically the "media: mediatek: vcodec" segment. The issue generates a smatch static checker warning on the "vdec_h264_req_multi_if.c" file. When a framebuffer (fb) is NULL, it can result in a kernel crash, severely affecting the security and stability of the system. The issue is concerning since the H264 codec is a common video encoding standard used widely across the industry for video playback and recording. Kernel crashes not only disrupt system stability, but they can also pose potential security and data risks.

The Linux kernel team has resolved this vulnerability with the following patch

--- a/drivers/media/platform/mtk-vcodec/vdec_h264_req_multi_if.c
+++ b/drivers/media/platform/mtk-vcodec/vdec_h264_req_multi_if.c
@@ -74,6 +74,8 @@ static void h264_process_ref_list(struct
{
  struct vb2_v4l2_buffer *fb;
  
+ if (!dec->fb[ref_idx])
+   return;
  fb = &dec->fb[ref_idx]->vbuf;
  rp[refs] = &dec->dpb[fb->index].rec;

This patch addresses the smatch warning by checking if fb is NULL before accessing its values. In consequence, the kernel crash is avoided, and the system remains stable and secure.

The Linux kernel team provides the following sources for further information and background

1. Linux kernel source code: This link provides direct access to the Linux kernel source code, where one can find the complete patch history and details on the various vulnerabilities and fixes made across the kernel's components.
2. Linux media subsystem documentation: For a deeper understanding of the Linux kernel's media subsystem, developers and users can refer to the official documentation.
3. CVE-2024-47754 - Linux kernel entry: The official CVE entry outlining the vulnerability and its impact. This entry summarizes the issue and provides other relevant metadata.

Exploit Potential

Unaddressed, this vulnerability posed risks to the security and stability of systems leveraging the H264 codec in the Linux kernel. If exploited, threat actors could have potentially leveraged the kernel crash to gain unauthorized access to systems, disrupt services, or exfiltrate sensitive data. By detecting and patching the vulnerability, the Linux kernel team has effectively eliminated this avenue of exploitation, securing both individual and enterprise deployments of the affected systems.

Conclusion

The diligent work of the Linux kernel team has resulted in the identification and resolution of the CVE-2024-47754 vulnerability, restoring security and stability to the kernel's media subsystem. Users and administrators leveraging the H264 codec on Linux-based platforms can update their systems with the latest kernel version to implement this fix, safeguarding their systems against potential threats. It's essential to stay updated with the Linux kernel's latest patches and security advisories to ensure the continued security and optimal performance of your systems.

Timeline

Published on: 10/21/2024 13:15:05 UTC
Last modified on: 10/22/2024 16:10:21 UTC