CVE-2026-74443: drm/vmwgfx: bound DMA command body size against suffix pointer

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

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

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

drm/vmwgfx: bound DMA command body size against suffix pointer

vmw_cmd_dma() locates the DMA suffix at

	(unsigned long) &cmd->body + header->size - sizeof(*suffix)

without checking that header->size is large enough to contain both
cmd->body and the suffix.  An undersized header makes the suffix
pointer underflow back into the previous command in the bounce
buffer.  The verifier later writes suffix->maximumOffset, clobbering
verified fields of an already-relocated earlier command -- a TOCTOU
on the device-visible command stream that lets one command rewrite
another's GMR id, surface id, or other authenticated fields.

Reject the command if the body is too small for the suffix to fit.

The Linux kernel CVE team has assigned CVE-2026-74443 to this issue.


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

	Issue introduced in 2.6.33 with commit 4e4ddd47774313accc86b233d6ca2c6a9037a671 and fixed in 6.6.151 with commit 036e16ada95389bdc30f41068af04c1d0872fad0
	Issue introduced in 2.6.33 with commit 4e4ddd47774313accc86b233d6ca2c6a9037a671 and fixed in 6.12.103 with commit d5d7ada4e1296b00d89fe82b2ca850cc7809d6f7
	Issue introduced in 2.6.33 with commit 4e4ddd47774313accc86b233d6ca2c6a9037a671 and fixed in 6.18.44 with commit 7e40e6120fb232a10b543ffd994e5c6d8f3a2cc6
	Issue introduced in 2.6.33 with commit 4e4ddd47774313accc86b233d6ca2c6a9037a671 and fixed in 7.1.8 with commit 9759da60e38d7b9db44dc92713e4e0391883d221
	Issue introduced in 2.6.33 with commit 4e4ddd47774313accc86b233d6ca2c6a9037a671 and fixed in 7.2-rc6 with commit f4f1db96bfd68b81053693ba53405b6f510ac16c

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-2026-74443
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_execbuf.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/036e16ada95389bdc30f41068af04c1d0872fad0
	https://git.kernel.org/stable/c/d5d7ada4e1296b00d89fe82b2ca850cc7809d6f7
	https://git.kernel.org/stable/c/7e40e6120fb232a10b543ffd994e5c6d8f3a2cc6
	https://git.kernel.org/stable/c/9759da60e38d7b9db44dc92713e4e0391883d221
	https://git.kernel.org/stable/c/f4f1db96bfd68b81053693ba53405b6f510ac16c