CVE-2021-47108

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