GHSA-VHJQ-V866-4C7F

Vulnerability from github – Published: 2026-06-29 06:31 – Updated: 2026-07-06 21:30
VLAI
Details

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

agp/amd64: Fix broken error propagation in agp_amd64_probe()

A NULL pointer dereference was observed in the AMD64 AGP driver when running in a virtualized environment (e.g. qemu/kvm) without a physical AMD northbridge. The crash occurs in amd64_fetch_size() when attempting to dereference the pointer returned by node_to_amd_nb(0).

The root cause of this crash is broken error propagation in agp_amd64_probe(): When no AMD northbridges are found, cache_nbs() correctly returns -ENODEV. However, the probe function erroneously checks the return value against exactly -1, rather than < 0.

As a result, the hardware absence error is masked, allowing the driver to improperly proceed with initialization. It eventually calls agp_add_bridge(), which invokes amd64_fetch_size(). Since the hardware does not exist, node_to_amd_nb(0) returns NULL, leading to a General Protection Fault (GPF) when accessing its ->misc member.

Fix the issue by correcting the error check in agp_amd64_probe() to abort properly when cache_nbs() returns any negative error code. This prevents the driver from erroneously proceeding without hardware, thereby avoiding the subsequent NULL pointer dereference at its source.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-53325"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-29T06:16:33Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nagp/amd64: Fix broken error propagation in agp_amd64_probe()\n\nA NULL pointer dereference was observed in the AMD64 AGP driver when\nrunning in a virtualized environment (e.g. qemu/kvm) without a physical\nAMD northbridge. The crash occurs in amd64_fetch_size() when attempting\nto dereference the pointer returned by node_to_amd_nb(0).\n\nThe root cause of this crash is broken error propagation in\nagp_amd64_probe(): When no AMD northbridges are found, cache_nbs()\ncorrectly returns -ENODEV. However, the probe function erroneously\nchecks the return value against exactly -1, rather than \u003c 0.\n\nAs a result, the hardware absence error is masked, allowing the driver\nto improperly proceed with initialization. It eventually calls\nagp_add_bridge(), which invokes amd64_fetch_size(). Since the hardware\ndoes not exist, node_to_amd_nb(0) returns NULL, leading to a General\nProtection Fault (GPF) when accessing its -\u003emisc member.\n\nFix the issue by correcting the error check in agp_amd64_probe() to\nabort properly when cache_nbs() returns any negative error code. This\nprevents the driver from erroneously proceeding without hardware, thereby\navoiding the subsequent NULL pointer dereference at its source.",
  "id": "GHSA-vhjq-v866-4c7f",
  "modified": "2026-07-06T21:30:27Z",
  "published": "2026-06-29T06:31:49Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53325"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0aa9b27c454c53074cde592eaceb442d30341585"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1d7d45050e14083c1de1460c93f4063c1f0bca7b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3e844a63668d1c3d10a9d347d7ebf161b2f91c84"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/53483a9f4ee9eeb18aa866ec16cce79e136987e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/564b3b3f6565313eb6fa5355ffd037d6fb27897f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b08472db93b1ccff84a7adec5779d47f0e9d3a30"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ce800993af477fc24187349c6a20d3073140b759"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cefe535a60a2e00e09f4b2689b0c8ffc6912459a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eb045714bc6a2bbb0befb7a31b996a196e188869"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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