Subject: CVE-2024-46710: drm/vmwgfx: Prevent unmapping active read buffers

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

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

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

drm/vmwgfx: Prevent unmapping active read buffers

The kms paths keep a persistent map active to read and compare the cursor
buffer. These maps can race with each other in simple scenario where:
a) buffer "a" mapped for update
b) buffer "a" mapped for compare
c) do the compare
d) unmap "a" for compare
e) update the cursor
f) unmap "a" for update
At step "e" the buffer has been unmapped and the read contents is bogus.

Prevent unmapping of active read buffers by simply keeping a count of
how many paths have currently active maps and unmap only when the count
reaches 0.

The Linux kernel CVE team has assigned CVE-2024-46710 to this issue.

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

	Issue introduced in 5.19 with commit 485d98d472d5 and fixed in 6.1.113 with commit 58a3714db4d9
	Issue introduced in 5.19 with commit 485d98d472d5 and fixed in 6.6.54 with commit 0851b1ec650a
	Issue introduced in 5.19 with commit 485d98d472d5 and fixed in 6.10.8 with commit d5228d158e4c
	Issue introduced in 5.19 with commit 485d98d472d5 and fixed in 6.11 with commit aba07b9a0587

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-2024-46710
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/vmwgfx/vmwgfx_bo.c
	drivers/gpu/drm/vmwgfx/vmwgfx_bo.h

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/58a3714db4d9dcaeb9fc4905141e17b9f536c0a5
	https://git.kernel.org/stable/c/0851b1ec650adadcaa23ec96daad95a55bf966f0
	https://git.kernel.org/stable/c/d5228d158e4c0b1663b3983044913c15c3d0135e
	https://git.kernel.org/stable/c/aba07b9a0587f50e5d3346eaa19019cf3f86c0ea