drm: Fix framebuffer leak

Do not leak framebuffer if client provided crtc id found invalid.
Signed-off-by: Nikhil Mahale <nmahale@nvidia.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1502250781-5779-1-git-send-email-nmahale@nvidia.com

drivers/gpu/drm/drm_plane.c

@@ -601,6 +601,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
 
 		crtc = drm_crtc_find(dev, plane_req->crtc_id);
 		if (!crtc) {
+			drm_framebuffer_put(fb);
 			DRM_DEBUG_KMS("Unknown crtc ID %d\n",
 				      plane_req->crtc_id);
 			return -ENOENT;