Bug 2309786 (CVE-2024-44955)

Summary: CVE-2024-44955 kernel: drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Bug Depends On: 2309876    
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Description OSIDB Bzimport 2024-09-04 19:20:46 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[Why]
When unplug one of monitors connected after mst hub, encounter null pointer dereference.

It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
commit new state which directly referring to info stored in dc_sink will cause null pointer
dereference.

[how]
Remove redundant checking condition. Relevant condition should already be covered by checking
if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.
Comment 1 Robb Gatica 2024-09-04 20:25:31 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024090412-CVE-2024-44955-20e8@gregkh/T