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

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-04 · updated 2026-06-17
Weakness: CWE-476

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.

Affected products

Linux kernel: from 5.14 before 5.15.12; 5.16-rc1, 5.16-rc2, 5.16-rc3, 5.16-rc4, 5.16-rc5, 5.16-rc6 — fixed in 5.15.12

How to fix

Upgrade to a fixed version: Linux kernel 5.15.12. Check the vendor advisory for mitigations.

References

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