GHSA-833C-QFXR-5PP5

Vulnerability from github – Published: 2025-07-25 15:30 – Updated: 2025-11-19 21:31
VLAI?
Details

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

video: screen_info: Relocate framebuffers behind PCI bridges

Apply PCI host-bridge window offsets to screen_info framebuffers. Fixes invalid access to I/O memory.

Resources behind a PCI host bridge can be relocated by a certain offset in the kernel's CPU address range used for I/O. The framebuffer memory range stored in screen_info refers to the CPU addresses as seen during boot (where the offset is 0). During boot up, firmware may assign a different memory offset to the PCI host bridge and thereby relocating the framebuffer address of the PCI graphics device as seen by the kernel. The information in screen_info must be updated as well.

The helper pcibios_bus_to_resource() performs the relocation of the screen_info's framebuffer resource (given in PCI bus addresses). The result matches the I/O-memory resource of the PCI graphics device (given in CPU addresses). As before, we store away the information necessary to later update the information in screen_info itself.

Commit 78aa89d1dfba ("firmware/sysfb: Update screen_info for relocated EFI framebuffers") added the code for updating screen_info. It is based on similar functionality that pre-existed in efifb. Efifb uses a pointer to the PCI resource, while the newer code does a memcpy of the region. Hence efifb sees any updates to the PCI resource and avoids the issue.

v3: - Only use struct pci_bus_region for PCI bus addresses (Bjorn) - Clarify address semantics in commit messages and comments (Bjorn) v2: - Fixed tags (Takashi, Ivan) - Updated information on efifb

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-2025-38427"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-401"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-25T15:15:27Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvideo: screen_info: Relocate framebuffers behind PCI bridges\n\nApply PCI host-bridge window offsets to screen_info framebuffers. Fixes\ninvalid access to I/O memory.\n\nResources behind a PCI host bridge can be relocated by a certain offset\nin the kernel\u0027s CPU address range used for I/O. The framebuffer memory\nrange stored in screen_info refers to the CPU addresses as seen during\nboot (where the offset is 0). During boot up, firmware may assign a\ndifferent memory offset to the PCI host bridge and thereby relocating\nthe framebuffer address of the PCI graphics device as seen by the kernel.\nThe information in screen_info must be updated as well.\n\nThe helper pcibios_bus_to_resource() performs the relocation of the\nscreen_info\u0027s framebuffer resource (given in PCI bus addresses). The\nresult matches the I/O-memory resource of the PCI graphics device (given\nin CPU addresses). As before, we store away the information necessary to\nlater update the information in screen_info itself.\n\nCommit 78aa89d1dfba (\"firmware/sysfb: Update screen_info for relocated\nEFI framebuffers\") added the code for updating screen_info. It is based\non similar functionality that pre-existed in efifb. Efifb uses a pointer\nto the PCI resource, while the newer code does a memcpy of the region.\nHence efifb sees any updates to the PCI resource and avoids the issue.\n\nv3:\n- Only use struct pci_bus_region for PCI bus addresses (Bjorn)\n- Clarify address semantics in commit messages and comments (Bjorn)\nv2:\n- Fixed tags (Takashi, Ivan)\n- Updated information on efifb",
  "id": "GHSA-833c-qfxr-5pp5",
  "modified": "2025-11-19T21:31:17Z",
  "published": "2025-07-25T15:30:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38427"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2f29b5c231011b94007d2c8a6d793992f2275db1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c70e3ad85d2890d8af375333699429de26327f2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aeda386d86d79269a08f470dbdc53d13a91e51fa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc3cc41ed67054a03134bea42408c720eec0fa04"
    }
  ],
  "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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