CVE-2026-72362: drm/xe/pt: Fix NULL pointer dereference in xe_pt_zap_ptes_entry()

CVE-2026-72362: drm/xe/pt: Fix NULL pointer dereference in xe_pt_zap_ptes_entry()

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

drm/xe/pt: Fix NULL pointer dereference in xe_pt_zap_ptes_entry()

The page-table walk framework may pass a NULL *child pointer for
unpopulated entries. xe_pt_zap_ptes_entry() called container_of(*child)
before checking for NULL, then dereferenced the result, causing a crash.

Move the container_of() call after a NULL guard, so the function returns
early instead of proceeding with an invalid pointer. XE_WARN_ON is kept
to help root cause the issue, but we now bail instead of crashing the
driver.

v2: Comment that triggering XE_WARN_ON is unexpected behavior (Matt Brost)

(cherry picked from commit b9297d19d9df5d4b6c994648570c5dcd1cac68ff)

The Linux kernel CVE team has assigned CVE-2026-72362 to this issue.


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

	Issue introduced in 6.8 with commit dd08ebf6c3525a7ea2186e636df064ea47281987 and fixed in 6.12.97 with commit ff330ce16c846b70164ff0eb544c81219d4c5c08
	Issue introduced in 6.8 with commit dd08ebf6c3525a7ea2186e636df064ea47281987 and fixed in 6.18.40 with commit 78b1074966d290d4517f42bc81e13c4349368d12
	Issue introduced in 6.8 with commit dd08ebf6c3525a7ea2186e636df064ea47281987 and fixed in 7.1.5 with commit d94b9922b2ae5ee6e900f8da0bd537b251c6110c
	Issue introduced in 6.8 with commit dd08ebf6c3525a7ea2186e636df064ea47281987 and fixed in 7.2-rc2 with commit 3feeb667197bd58a17f4edfdbcad249ffcb3c864

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-2026-72362
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/xe/xe_pt.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/ff330ce16c846b70164ff0eb544c81219d4c5c08
	https://git.kernel.org/stable/c/78b1074966d290d4517f42bc81e13c4349368d12
	https://git.kernel.org/stable/c/d94b9922b2ae5ee6e900f8da0bd537b251c6110c
	https://git.kernel.org/stable/c/3feeb667197bd58a17f4edfdbcad249ffcb3c864