Bug 2317580 (CVE-2024-46870)

Summary: CVE-2024-46870 kernel: drm/amd/display: Disable DMCUB timeout for DCN35
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: 2318117    
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Description OSIDB Bzimport 2024-10-09 14:42:05 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Disable DMCUB timeout for DCN35

[Why]
DMCUB can intermittently take longer than expected to process commands.

Old ASIC policy was to continue while logging a diagnostic error - which
works fine for ASIC without IPS, but with IPS this could lead to a race
condition where we attempt to access DCN state while it's inaccessible,
leading to a system hang when the NIU port is not disabled or register
accesses that timeout and the display configuration in an undefined
state.

[How]
We need to investigate why these accesses take longer than expected, but
for now we should disable the timeout on DCN35 to avoid this race
condition. Since the waits happen only at lower interrupt levels the
risk of taking too long at higher IRQ and causing a system watchdog
timeout are minimal.
Comment 1 Mauro Matteo Cascella 2024-10-11 16:38:07 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024100958-CVE-2024-46870-f347@gregkh/T