Bug 2323928 (CVE-2024-50090)

Summary: CVE-2024-50090 kernel: drm/xe/oa: Fix overflow in oa batch buffer
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Bug Depends On: 2324031    
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Description OSIDB Bzimport 2024-11-05 18:02:45 UTC
In the Linux kernel, the following vulnerability has been resolved:

drm/xe/oa: Fix overflow in oa batch buffer

By default xe_bb_create_job() appends a MI_BATCH_BUFFER_END to batch
buffer, this is not a problem if batch buffer is only used once but
oa reuses the batch buffer for the same metric and at each call
it appends a MI_BATCH_BUFFER_END, printing the warning below and then
overflowing.

[  381.072016] ------------[ cut here ]------------
[  381.072019] xe 0000:00:02.0: [drm] Assertion `bb->len * 4 + bb_prefetch(q->gt) <= size` failed!
               platform: LUNARLAKE subplatform: 1
               graphics: Xe2_LPG / Xe2_HPG 20.04 step B0
               media: Xe2_LPM / Xe2_HPM 20.00 step B0
               tile: 0 VRAM 0 B
               GT: 0 type 1

So here checking if batch buffer already have MI_BATCH_BUFFER_END if
not append it.

v2:
- simply fix, suggestion from Ashutosh

(cherry picked from commit 9ba0e0f30ca42a98af3689460063edfb6315718a)