CVE-2025-68296
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-16

Last updated on: 2025-12-18

Assigner: kernel.org

Description
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.
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Meta Information
Published
2025-12-16
Last Modified
2025-12-18
Generated
2026-05-07
AI Q&A
2025-12-16
EPSS Evaluated
2026-05-05
NVD
CVE-2025-68296
EUVD
EUVD-2025-203784
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is a race condition in the Linux kernel's framebuffer console (fbcon) setup related to VGA switcheroo. The issue occurs because vga_switcheroo_client_fb_set() is called before the framebuffer is registered, causing the fbcon to use an invalid node value (-1). This leads to out-of-bounds access in fbcon_remap_all() when switching VGA outputs. The fix involves moving the call to vga_switcheroo_client_fb_set() to after the framebuffer registration and protecting it with the console lock to avoid the race condition.


How can this vulnerability impact me? :

This vulnerability can cause out-of-bounds memory access during VGA output switching, potentially leading to system instability or crashes. It affects systems using certain graphics drivers (amdgpu, i915, nouveau, radeon) that support VGA switcheroo. The race condition could result in improper framebuffer switching, which may disrupt display output or cause kernel errors.


What immediate steps should I take to mitigate this vulnerability?

Apply the patch or update that moves the vga_switcheroo_client_fb_set() call under fbcon_fb_registered(), ensuring it holds the console lock to avoid the race condition. This fix serializes the helper with VGA switcheroo's call to fbcon_remap_all(), preventing out-of-bounds access and improper framebuffer switching. If you use amdgpu, i915, nouveau, or radeon drivers, ensure your Linux kernel is updated with this fix.


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