CVE-2026-68243: drm/i915/gem: Fix NULL deref in I915_CONTEXT_PARAM_SSEU

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

drm/i915/gem: Fix NULL deref in I915_CONTEXT_PARAM_SSEU

Setting context engine slot N into I915_ENGINE_CLASS_INVALID /
I915_ENGINE_CLASS_INVALID_NONE and attempting to apply
I915_CONTEXT_PARAM_SSEU to the same slot N will deref NULL.
Fix that.

Discovered using AI-assisted static analysis confirmed by
Intel Product Security.

(cherry picked from commit 36eda5b5c2d40da41cc0a5403c26986237cf9e87)

The Linux kernel CVE team has assigned CVE-2026-68243 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.15 with commit d4433c7600f794623d6802395542cf4ca4f1b1f9 and fixed in 6.6.148 with commit edd2edaca52ada833c341c8b264aaea9dd93369c
	Issue introduced in 5.15 with commit d4433c7600f794623d6802395542cf4ca4f1b1f9 and fixed in 6.12.101 with commit 9923c223d38fcd9602f41cc31d480e5299d9a38e
	Issue introduced in 5.15 with commit d4433c7600f794623d6802395542cf4ca4f1b1f9 and fixed in 6.18.42 with commit 726f27bca93e6c83b263542669132ee1d0eb693e
	Issue introduced in 5.15 with commit d4433c7600f794623d6802395542cf4ca4f1b1f9 and fixed in 7.1.6 with commit 97f236379f06a5082d37c6a764edd56bb58a94cd
	Issue introduced in 5.15 with commit d4433c7600f794623d6802395542cf4ca4f1b1f9 and fixed in 7.2-rc3 with commit 2b56757a9a7456825eb668fde92299e01c5e2721

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-68243
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/gpu/drm/i915/gem/i915_gem_context.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/edd2edaca52ada833c341c8b264aaea9dd93369c
	https://git.kernel.org/stable/c/9923c223d38fcd9602f41cc31d480e5299d9a38e
	https://git.kernel.org/stable/c/726f27bca93e6c83b263542669132ee1d0eb693e
	https://git.kernel.org/stable/c/97f236379f06a5082d37c6a764edd56bb58a94cd
	https://git.kernel.org/stable/c/2b56757a9a7456825eb668fde92299e01c5e2721