drm/vmwgfx: Validate the box size for the snooped cursor

drm/vmwgfx: Validate the box size for the snooped cursor

Origin: https://git.kernel.org/linus/4cf949c7fafe21e085a4ee386bb2dade9067316e
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2022-36280

Invalid userspace dma surface copies could potentially overflow
the memcpy from the surface to the snooped image leading to crashes.
To fix it the dimensions of the copybox have to be validated
against the expected size of the snooped cursor.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: 2ac863719e51 ("vmwgfx: Snoop DMA transfers with non-covering sizes")
Cc: <stable@vger.kernel.org> # v3.2+
Reviewed-by: Michael Banack <banackm@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221026031936.1004280-1-zack@kde.org
Gbp-Pq: Topic bugfix/x86
Gbp-Pq: Name drm-vmwgfx-Validate-the-box-size-for-the-snooped-cur.patch