CVE-2021-47108: drm/mediatek: hdmi: Perform NULL pointer check for mtk_hdmi_conf

Vulnerability summary

CVE-2021-47108 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.6% of scored vulnerabilities.

Timeline

1. 04-03-2024
   PublishedVulnerability first disclosed.
2. 11-05-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.