Bug 2307876 (CVE-2024-43903)

Summary: CVE-2024-43903 kernel: drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor_update
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A NULL pointer dereference vulnerability was found in the AMD Display (drm/amd/display) subsystem of the Linux kernel with the "afb" variable in the amdgpu_dm_plane_handle_cursor_update() function in amdgpu_dm_plane.c file. This flaw allows an attacker to craft a situation where the "afb" variable is NULL but is used later in the function. This issue can lead to a kernel panic or a system crash when dereferencing the NULL pointer, impacting system availability. It can also disrupt services reliant on the graphical subsystem, affecting performance and user experience.
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Bug Depends On: 2308115    
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Description OSIDB Bzimport 2024-08-26 11:21:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor_update

This commit adds a null check for the 'afb' variable in the
amdgpu_dm_plane_handle_cursor_update function. Previously, 'afb' was
assumed to be null, but was used later in the code without a null check.
This could potentially lead to a null pointer dereference.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_plane.c:1298 amdgpu_dm_plane_handle_cursor_update() error: we previously assumed 'afb' could be null (see line 1252)
Comment 1 Mauro Matteo Cascella 2024-08-27 11:14:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024082620-CVE-2024-43903-3644@gregkh/T