Linux Kernel up to 5.15.11 mediatek mtk_hdmi_bridge_mode_valid null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel up to 5.15.11 and classified as critical. Affected by this issue is the function mtk_hdmi_bridge_mode_valid of the component mediatek. This manipulation causes null pointer dereference. This vulnerability is registered as CVE-2021-47108. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 5.15.11 (Operating System) and classified as critical. Affected by this vulnerability is the function mtk_hdmi_bridge_mode_valid of the component mediatek. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: drm/mediatek: hdmi: Perform NULL pointer check for mtk_hdmi_conf In commit 41ca9caaae0b ("drm/mediatek: hdmi: Add check for CEA modes only") a check for CEA modes was added to function mtk_hdmi_bridge_mode_valid() in order to address possible issues on MT8167; moreover, with commit c91026a938c2 ("drm/mediatek: hdmi: Add optional limit on maximal HDMI mode clock") another similar check was introduced. Unfortunately though, at the time of writing, MT8173 does not provide any mtk_hdmi_conf structure and this is crashing the kernel with NULL pointer upon entering mtk_hdmi_bridge_mode_valid(), which happens as soon as a HDMI cable gets plugged in. To fix this regression, add a NULL pointer check for hdmi->conf in the said function, restoring HDMI functionality and avoiding NULL pointer kernel panics.

The weakness was published 03/04/2024. The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2021-47108. Technical details are known, but no exploit is available.

Upgrading to version 5.15.12 or 5.16 eliminates this vulnerability. Applying the patch 71d07ebc5000/3b8e19a0aa39 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

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