CVE-2026-80888: drm/vmwgfx: drop dma_buf reference on foreign-fd prime import

CVE-2026-80888: drm/vmwgfx: drop dma_buf reference on foreign-fd prime import

[Greg Kroah-Hartman]

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

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

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

drm/vmwgfx: drop dma_buf reference on foreign-fd prime import

ttm_prime_fd_to_handle() returns -ENOSYS when the imported fd's
dma_buf->ops do not match the ttm_object_device's ops, but does so
without releasing the reference acquired by dma_buf_get().  Any
unprivileged renderD client passing a non-vmwgfx prime fd through the
DRM_VMW_GB_SURFACE_REF{,_EXT} path leaks one dma_buf reference per
call and indefinitely pins the foreign exporter's GEM resources.

Funnel the error path through the existing dma_buf_put() so the
reference is always dropped.

The Linux kernel CVE team has assigned CVE-2026-80888 to this issue.


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

	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 6.1.183 with commit 619c3cfa88e09603a13d918f754808db2dda7057
	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 6.6.151 with commit c1c22fca0a0896a452a7cb92422d67babd65b4be
	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 6.12.103 with commit a1e972fa94c3a8069e022c67b9d97c7aa7b05293
	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 6.18.44 with commit a8434b145b1e467940334c58c00af241e9494c5f
	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 7.1.8 with commit 4df39eb99bb47d1f24d1952c23b21b10988356bf
	Issue introduced in 3.13 with commit 65981f7681abdf92b25942222b629b9c512d0705 and fixed in 7.2 with commit f739416dc555fa205a785e5135d73fa39b26f35d

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-2026-80888
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/ttm_object.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/619c3cfa88e09603a13d918f754808db2dda7057
	https://git.kernel.org/stable/c/c1c22fca0a0896a452a7cb92422d67babd65b4be
	https://git.kernel.org/stable/c/a1e972fa94c3a8069e022c67b9d97c7aa7b05293
	https://git.kernel.org/stable/c/a8434b145b1e467940334c58c00af241e9494c5f
	https://git.kernel.org/stable/c/4df39eb99bb47d1f24d1952c23b21b10988356bf
	https://git.kernel.org/stable/c/f739416dc555fa205a785e5135d73fa39b26f35d