CVE-2025-68296 (GCVE-0-2025-68296)

Vulnerability from cvelistv5 – Published: 2025-12-16 15:06 – Updated: 2025-12-16 15:06
VLAI?
Title
drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
Summary
In the Linux kernel, the following vulnerability has been resolved: drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB access in fbcon_remap_all(). Without holding the console lock the call races with switching outputs. VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon function uses struct fb_info.node, which is set by register_framebuffer(). As the fb-helper code currently sets up VGA switcheroo before registering the framebuffer, the value of node is -1 and therefore not a legal value. For example, fbcon uses the value within set_con2fb_map() [1] as an index into an array. Moving vga_switcheroo_client_fb_set() after register_framebuffer() can result in VGA switching that does not switch fbcon correctly. Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(), which already holds the console lock. Fbdev calls fbcon_fb_registered() from within register_framebuffer(). Serializes the helper with VGA switcheroo's call to fbcon_remap_all(). Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info as parameter, it really only needs the contained fbcon state. Moving the call to fbcon initialization is therefore cleaner than before. Only amdgpu, i915, nouveau and radeon support vga_switcheroo. For all other drivers, this change does nothing.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 6a9ee8af344e3bd7dbd61e67037096cdf7f83289 , < 482330f8261b4bea8146d9bd69c1199e5dfcbb5c (git)
Affected: 6a9ee8af344e3bd7dbd61e67037096cdf7f83289 , < 05814c389b53d2f3a0b9eeb90ba7a05ba77c4c2a (git)
Affected: 6a9ee8af344e3bd7dbd61e67037096cdf7f83289 , < eb76d0f5553575599561010f24c277cc5b31d003 (git)
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    Linux Linux Affected: 2.6.34
Unaffected: 0 , < 2.6.34 (semver)
Unaffected: 6.12.61 , ≤ 6.12.* (semver)
Unaffected: 6.17.11 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_fb_helper.c",
            "drivers/video/fbdev/core/fbcon.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "482330f8261b4bea8146d9bd69c1199e5dfcbb5c",
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              "versionType": "git"
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            "drivers/video/fbdev/core/fbcon.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "2.6.34"
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              "version": "0",
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              "status": "unaffected",
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.17.11",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
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                  "versionStartIncluding": "2.6.34",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup\n\nProtect vga_switcheroo_client_fb_set() with console lock. Avoids OOB\naccess in fbcon_remap_all(). Without holding the console lock the call\nraces with switching outputs.\n\nVGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon\nfunction uses struct fb_info.node, which is set by register_framebuffer().\nAs the fb-helper code currently sets up VGA switcheroo before registering\nthe framebuffer, the value of node is -1 and therefore not a legal value.\nFor example, fbcon uses the value within set_con2fb_map() [1] as an index\ninto an array.\n\nMoving vga_switcheroo_client_fb_set() after register_framebuffer() can\nresult in VGA switching that does not switch fbcon correctly.\n\nTherefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),\nwhich already holds the console lock. Fbdev calls fbcon_fb_registered()\nfrom within register_framebuffer(). Serializes the helper with VGA\nswitcheroo\u0027s call to fbcon_remap_all().\n\nAlthough vga_switcheroo_client_fb_set() takes an instance of struct fb_info\nas parameter, it really only needs the contained fbcon state. Moving the\ncall to fbcon initialization is therefore cleaner than before. Only amdgpu,\ni915, nouveau and radeon support vga_switcheroo. For all other drivers,\nthis change does nothing."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-16T15:06:15.797Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/482330f8261b4bea8146d9bd69c1199e5dfcbb5c"
        },
        {
          "url": "https://git.kernel.org/stable/c/05814c389b53d2f3a0b9eeb90ba7a05ba77c4c2a"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb76d0f5553575599561010f24c277cc5b31d003"
        }
      ],
      "title": "drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68296",
    "datePublished": "2025-12-16T15:06:15.797Z",
    "dateReserved": "2025-12-16T14:48:05.293Z",
    "dateUpdated": "2025-12-16T15:06:15.797Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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