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

2024-03-0418:15:40

Linux

github.com

linux kernel

vulnerability

hdmi

null pointer check

mtk_hdmi_conf

commit

cea modes

mt8167

mt8173

kernel panics

AI Score

6.7

Confidence

Low

SSVC

Exploitation

none

Automatable

Technical Impact

partial

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

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