CVE-2023-52981

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

drm/i915: Fix request ref counting during error capture & debugfs dump

When GuC support was added to error capture, the reference counting

around the request object was broken. Fix it up.

The context based search manages the spinlocking around the search

internally. So it needs to grab the reference count internally as

well. The execlist only request based search relies on external

locking, so it needs an external reference count but within the

spinlock not outside it.

The only other caller of the context based search is the code for

dumping engine state to debugfs. That code wasn't previously getting

an explicit reference at all as it does everything while holding the

execlist specific spinlock. So, that needs updaing as well as that

spinlock doesn't help when using GuC submission. Rather than trying to

conditionally get/put depending on submission model, just change it to

always do the get/put.

v2: Explicitly do

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References