Vulnerability-Lookup

GHSA-WG36-23G4-V8G6

Vulnerability from github – Published: 2025-06-18 12:30 – Updated: 2025-11-19 15:31

Details

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

drm/fb-helper: Fix out-of-bounds access

Clip memory range to screen-buffer size to avoid out-of-bounds access in fbdev deferred I/O's damage handling.

Fbdev's deferred I/O can only track pages. From the range of pages, the damage handler computes the clipping rectangle for the display update. If the fbdev screen buffer ends near the beginning of a page, that page could contain more scanlines. The damage handler would then track these non-existing scanlines as dirty and provoke an out-of-bounds access during the screen update. Hence, clip the maximum memory range to the size of the screen buffer.

While at it, rename the variables min/max to min_off/max_off in drm_fb_helper_deferred_io(). This avoids confusion with the macros of the same name.

Severity

7.1 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2022-50221"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-06-18T11:15:53Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/fb-helper: Fix out-of-bounds access\n\nClip memory range to screen-buffer size to avoid out-of-bounds access\nin fbdev deferred I/O\u0027s damage handling.\n\nFbdev\u0027s deferred I/O can only track pages. From the range of pages, the\ndamage handler computes the clipping rectangle for the display update.\nIf the fbdev screen buffer ends near the beginning of a page, that page\ncould contain more scanlines. The damage handler would then track these\nnon-existing scanlines as dirty and provoke an out-of-bounds access\nduring the screen update. Hence, clip the maximum memory range to the\nsize of the screen buffer.\n\nWhile at it, rename the variables min/max to min_off/max_off in\ndrm_fb_helper_deferred_io(). This avoids confusion with the macros of\nthe same name.",
  "id": "GHSA-wg36-23g4-v8g6",
  "modified": "2025-11-19T15:31:31Z",
  "published": "2025-06-18T12:30:57Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-50221"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9c49ac792c639dbec0728b513329a32461f72253"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae25885bdf59fde40726863c57fd20e4a0642183"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2022-50221 (GCVE-0-2022-50221)

Vulnerability from cvelistv5 – Published: 2025-06-18 11:03 – Updated: 2026-08-05 08:57

Title

drm/fb-helper: Fix out-of-bounds access

Summary

In the Linux kernel, the following vulnerability has been resolved: drm/fb-helper: Fix out-of-bounds access Clip memory range to screen-buffer size to avoid out-of-bounds access in fbdev deferred I/O's damage handling. Fbdev's deferred I/O can only track pages. From the range of pages, the damage handler computes the clipping rectangle for the display update. If the fbdev screen buffer ends near the beginning of a page, that page could contain more scanlines. The damage handler would then track these non-existing scanlines as dirty and provoke an out-of-bounds access during the screen update. Hence, clip the maximum memory range to the size of the screen buffer. While at it, rename the variables min/max to min_off/max_off in drm_fb_helper_deferred_io(). This avoids confusion with the macros of the same name.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/9c49ac792c639dbec…
https://git.kernel.org/stable/c/ae25885bdf59fde40…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 67b723f5b74254d27962b1b59bddfee1584575ff , < 9c49ac792c639dbec0728b513329a32461f72253 (git) Affected: 67b723f5b74254d27962b1b59bddfee1584575ff , < ae25885bdf59fde40726863c57fd20e4a0642183 (git)
Linux	Linux	Affected: 5.18 Unaffected: 0 , < 5.18 (semver) Unaffected: 5.19.2 , ≤ 5.19.* (semver) Unaffected: 6.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_fb_helper.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9c49ac792c639dbec0728b513329a32461f72253",
              "status": "affected",
              "version": "67b723f5b74254d27962b1b59bddfee1584575ff",
              "versionType": "git"
            },
            {
              "lessThan": "ae25885bdf59fde40726863c57fd20e4a0642183",
              "status": "affected",
              "version": "67b723f5b74254d27962b1b59bddfee1584575ff",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_fb_helper.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.19.*",
              "status": "unaffected",
              "version": "5.19.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.19.2",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.0",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/fb-helper: Fix out-of-bounds access\n\nClip memory range to screen-buffer size to avoid out-of-bounds access\nin fbdev deferred I/O\u0027s damage handling.\n\nFbdev\u0027s deferred I/O can only track pages. From the range of pages, the\ndamage handler computes the clipping rectangle for the display update.\nIf the fbdev screen buffer ends near the beginning of a page, that page\ncould contain more scanlines. The damage handler would then track these\nnon-existing scanlines as dirty and provoke an out-of-bounds access\nduring the screen update. Hence, clip the maximum memory range to the\nsize of the screen buffer.\n\nWhile at it, rename the variables min/max to min_off/max_off in\ndrm_fb_helper_deferred_io(). This avoids confusion with the macros of\nthe same name."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached by opening /dev/fbN, mmap\u0027ing the fbdev shadow buffer, and dirtying pages so fb_deferred_io_work calls drm_fb_helper_deferred_io(); that is a local device/syscall path with no network or adjacent-protocol entry.\nAC:L - On affected shadow-fbdev configurations whose screen_size is not page-aligned (common modes such as 1366x768x32), writing the last mapped page and flushing deferred I/O (or fsync) reliably enlarges the damage clip past the buffer; no race or attacker-uncontrollable layout is required.\nPR:L - fb_open() has no capability check; access is DAC on /dev/fbN (typically 660 root:video), which ordinary desktop, Android, and embedded graphics users hold via the video group\u2014basic local privileges, not real root.\nUI:N - The attacker opens the framebuffer, mmaps it, and dirties the last page themselves; no separate victim action is required.\nS:U - Corruption stays in host kernel vmalloc/GEM memory under the same OS authority; this is not a VM escape, IOMMU bypass, or other cross-boundary impact.\nC:H - drm_fb_helper_damage_blit_real() reads past the vzalloc\u0027d shadow buffer into adjacent kernel memory (often kilobytes for a full extra scanline), an out-of-bounds read well beyond a few bytes that can disclose neighboring contents into the blit/display path.\nI:H - The same oversized clip drives iosys_map_memcpy_to() past the logical framebuffer into memory beyond the page-aligned GEM allocation (e.g. ~3KB past the BO for 1366x768x32), a kernel out-of-bounds write exploitable for heap corruption/control-flow impact.\nA:H - Accesses past the shadow/GEM allocations into unmapped vmalloc/guard regions can oops or panic the kernel, so availability impact is High."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:57:46.137Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9c49ac792c639dbec0728b513329a32461f72253"
        },
        {
          "url": "https://git.kernel.org/stable/c/ae25885bdf59fde40726863c57fd20e4a0642183"
        }
      ],
      "title": "drm/fb-helper: Fix out-of-bounds access",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2022-50221",
    "datePublished": "2025-06-18T11:03:56.096Z",
    "dateReserved": "2025-06-18T10:57:27.430Z",
    "dateUpdated": "2026-08-05T08:57:46.137Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

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