CVE-2025-39741: drm/xe/migrate: don't overflow max copy size

CVE-2025-39741: drm/xe/migrate: don't overflow max copy size

[Greg Kroah-Hartman]

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

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

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

drm/xe/migrate: don't overflow max copy size

With non-page aligned copy, we need to use 4 byte aligned pitch, however
the size itself might still be close to our maximum of ~8M, and so the
dimensions of the copy can easily exceed the S16_MAX limit of the copy
command leading to the following assert:

xe 0000:03:00.0: [drm] Assertion `size / pitch <= ((s16)(((u16)~0U) >> 1))` failed!
platform: BATTLEMAGE subplatform: 1
graphics: Xe2_HPG 20.01 step A0
media: Xe2_HPM 13.01 step A1
tile: 0 VRAM 10.0 GiB
GT: 0 type 1

WARNING: CPU: 23 PID: 10605 at drivers/gpu/drm/xe/xe_migrate.c:673 emit_copy+0x4b5/0x4e0 [xe]

To fix this account for the pitch when calculating the number of current
bytes to copy.

(cherry picked from commit 8c2d61e0e916e077fda7e7b8e67f25ffe0f361fc)

The Linux kernel CVE team has assigned CVE-2025-39741 to this issue.


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

	Issue introduced in 6.16 with commit 270172f64b114451876c1b68912653e72ab99f38 and fixed in 6.16.2 with commit 7257cc6644d540130a46a61531a07a0517cace89
	Issue introduced in 6.16 with commit 270172f64b114451876c1b68912653e72ab99f38 and fixed in 6.17-rc2 with commit 4126cb327a2e3273c81fcef1c594c5b7b645c44c

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-2025-39741
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/7257cc6644d540130a46a61531a07a0517cace89
	https://git.kernel.org/stable/c/4126cb327a2e3273c81fcef1c594c5b7b645c44c