fkie_cve-2025-68296
Vulnerability from fkie_nvd
Published
2025-12-16 16:16
Modified
2025-12-18 15:08
Severity ?
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/05814c389b53d2f3a0b9eeb90ba7a05ba77c4c2a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/482330f8261b4bea8146d9bd69c1199e5dfcbb5c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eb76d0f5553575599561010f24c277cc5b31d003
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2025-68296",
  "lastModified": "2025-12-18T15:08:06.237",
  "metrics": {},
  "published": "2025-12-16T16:16:08.540",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/05814c389b53d2f3a0b9eeb90ba7a05ba77c4c2a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/482330f8261b4bea8146d9bd69c1199e5dfcbb5c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eb76d0f5553575599561010f24c277cc5b31d003"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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