linux-cve-announce - CVE-2025-38690: drm/xe/migrate: prevent infinite recursion

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Message-ID: <2025090449-CVE-2025-38690-ea6c@gregkh>
Date: Thu,  4 Sep 2025 17:32:55 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38690: drm/xe/migrate: prevent infinite recursion

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

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

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

drm/xe/migrate: prevent infinite recursion

If the buf + offset is not aligned to XE_CAHELINE_BYTES we fallback to
using a bounce buffer. However the bounce buffer here is allocated on
the stack, and the only alignment requirement here is that it's
naturally aligned to u8, and not XE_CACHELINE_BYTES. If the bounce
buffer is also misaligned we then recurse back into the function again,
however the new bounce buffer might also not be aligned, and might never
be until we eventually blow through the stack, as we keep recursing.

Instead of using the stack use kmalloc, which should respect the
power-of-two alignment request here. Fixes a kernel panic when
triggering this path through eudebug.

v2 (Stuart):
 - Add build bug check for power-of-two restriction
 - s/EINVAL/ENOMEM/

(cherry picked from commit 38b34e928a08ba594c4bbf7118aa3aadacd62fff)

The Linux kernel CVE team has assigned CVE-2025-38690 to this issue.

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

	Issue introduced in 6.16 with commit 270172f64b114451876c1b68912653e72ab99f38 and fixed in 6.16.2 with commit 89f511c024879c5812cc0c010a6663b5e49950f3
	Issue introduced in 6.16 with commit 270172f64b114451876c1b68912653e72ab99f38 and fixed in 6.17-rc2 with commit 9d7a1cbebbb691891671def57407ba2f8ee914e8

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-2025-38690
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_migrate.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/89f511c024879c5812cc0c010a6663b5e49950f3
	https://git.kernel.org/stable/c/9d7a1cbebbb691891671def57407ba2f8ee914e8