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.