CVE-2021-47444 drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read

2024-05-2206:19:37

Linux

www.cve.org

linux kernel

vulnerability resolved

drm/edid

connector_bad_edid()

bounds check

memory allocated

6.4 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

15.7%

JSON

In the Linux kernel, the following vulnerability has been resolved:

drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read

In commit e11f5bd8228f (“drm: Add support for DP 1.4 Compliance edid
corruption test”) the function connector_bad_edid() started assuming
that the memory for the EDID passed to it was big enough to hold
edid[0x7e] + 1 blocks of data (1 extra for the base block). It
completely ignored the fact that the function was passed num_blocks
which indicated how much memory had been allocated for the EDID.

Let’s fix this by adding a bounds check.

This is important for handling the case where there’s an error in the
first block of the EDID. In that case we will call
connector_bad_edid() without having re-allocated memory based on
edid[0x7e].

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/drm_edid.c"
    ],
    "versions": [
      {
        "version": "e11f5bd8228f",
        "lessThan": "a7b45024f66f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "e11f5bd8228f",
        "lessThan": "09f3946bb452",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "e11f5bd8228f",
        "lessThan": "97794170b696",
        "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/drm_edid.c"
    ],
    "versions": [
      {
        "version": "5.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.7",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.75",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14.14",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]