CVE-2026-74445: drm/vmwgfx: reject DX_BIND_QUERY without a DX context

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

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

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

drm/vmwgfx: reject DX_BIND_QUERY without a DX context

vmw_cmd_dx_bind_query() unconditionally dereferences
sw_context->dx_ctx_node->ctx.  Userspace can trigger a NULL pointer
dereference from any render-node fd by submitting an execbuf with
dx_context_handle == SVGA3D_INVALID_ID and a SVGA_3D_CMD_DX_BIND_QUERY
opcode in the command stream: dx_ctx_node is left NULL and the kernel
oopses on the assignment.  The same NULL is then re-read in
vmw_resources_reserve() via vmw_context_get_dx_query_mob().

All sibling DX handlers fail-close on a missing dx_ctx_node using
VMW_GET_CTX_NODE().  Use the same pattern here, returning -EINVAL up
front before any relocation state is published.

The Linux kernel CVE team has assigned CVE-2026-74445 to this issue.


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

	Issue introduced in 4.20 with commit 9c079b8ce8bf8e0394149eb39c78b04285644bcc and fixed in 6.6.151 with commit 7eae011829f94a76470ec76f016805f508437755
	Issue introduced in 4.20 with commit 9c079b8ce8bf8e0394149eb39c78b04285644bcc and fixed in 6.12.103 with commit 0634d50e8b398c25bd07c96b048e484d22688c26
	Issue introduced in 4.20 with commit 9c079b8ce8bf8e0394149eb39c78b04285644bcc and fixed in 6.18.44 with commit e479240a1e076ba1104236331abd62400bf1d495
	Issue introduced in 4.20 with commit 9c079b8ce8bf8e0394149eb39c78b04285644bcc and fixed in 7.1.8 with commit 6b1eb0b63cc153e1c0cb5ab8350950119be11947
	Issue introduced in 4.20 with commit 9c079b8ce8bf8e0394149eb39c78b04285644bcc and fixed in 7.2-rc6 with commit 55ec09c9ce10b1272802c7ab6c1be2ea0dbc68db

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-2026-74445
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/7eae011829f94a76470ec76f016805f508437755
	https://git.kernel.org/stable/c/0634d50e8b398c25bd07c96b048e484d22688c26
	https://git.kernel.org/stable/c/e479240a1e076ba1104236331abd62400bf1d495
	https://git.kernel.org/stable/c/6b1eb0b63cc153e1c0cb5ab8350950119be11947
	https://git.kernel.org/stable/c/55ec09c9ce10b1272802c7ab6c1be2ea0dbc68db