CVE-2024-49865: drm/xe/vm: move xa_alloc to prevent UAF

CVE-2024-49865: drm/xe/vm: move xa_alloc to prevent UAF

[Greg Kroah-Hartman]

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

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

drm/xe/vm: move xa_alloc to prevent UAF

Evil user can guess the next id of the vm before the ioctl completes and
then call vm destroy ioctl to trigger UAF since create ioctl is still
referencing the same vm. Move the xa_alloc all the way to the end to
prevent this.

v2:
 - Rebase

(cherry picked from commit dcfd3971327f3ee92765154baebbaece833d3ca9)

The Linux kernel CVE team has assigned CVE-2024-49865 to this issue.


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

	Issue introduced in 6.8 with commit dd08ebf6c352 and fixed in 6.11.3 with commit 09cf8901fc02
	Issue introduced in 6.8 with commit dd08ebf6c352 and fixed in 6.12-rc2 with commit 74231870cf49

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-2024-49865
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_vm.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/09cf8901fc0225898311b375cfcc67bae37ed5da
	https://git.kernel.org/stable/c/74231870cf4976f69e83aa24f48edb16619f652f