drm/vmwgfx: Handle surface check failure correctly

Currently if condition (!bo and !vmw_kms_srf_ok()) was met
we go to err_out with ret == 0.
err_out dereferences vfb if ret == 0, but in our case vfb is still NULL.

Fix this by assigning sensible error to ret.

Found by Linux Verification Center (linuxtesting.org) with SVACE

Signed-off-by: Nikolay Kuratov <[email protected]>
Cc: [email protected]
Fixes: 810b3e1 ("drm/vmwgfx: Support topology greater than texture size")
Signed-off-by: Zack Rusin <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Nikolay Kuratov

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -1510,6 +1510,7 @@ static struct drm_framebuffer *vmw_kms_fb_create(struct drm_device *dev,
 		DRM_ERROR("Surface size cannot exceed %dx%d\n",
 			dev_priv->texture_max_width,
 			dev_priv->texture_max_height);
+		ret = -EINVAL;
 		goto err_out;
 	}