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

2024-03-0418:15:40

Linux

www.cve.org

linux kernel

vulnerability

resolved

commit

mtk_hdmi_conf

cea modes

mt8167

mt8173

hdmi cable

regression

null pointer check

kernel panics

7.4 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

9.0%

JSON

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.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/gpu/drm/mediatek/mtk_hdmi.c"
    ],
    "versions": [
      {
        "version": "41ca9caaae0b",
        "lessThan": "71d07ebc5000",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "41ca9caaae0b",
        "lessThan": "3b8e19a0aa39",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/gpu/drm/mediatek/mtk_hdmi.c"
    ],
    "versions": [
      {
        "version": "5.14",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.14",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.12",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]