drm/vc4: Return -EINVAL on the overflow checks failing.

commit 6b8ac63847bc2f958dd93c09edc941a0118992d9 upstream.

By failing to set the errno, we'd continue on to trying to set up the
RCL, and then oops on trying to dereference the tile_bo that binning
validation should have set up.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Fixes: d5b1a78a772f ("drm/vc4: Add support for drawing 3D frames.")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/vc4/vc4_gem.c

@@ -601,6 +601,7 @@ vc4_get_bcl(struct drm_device *dev, struct vc4_exec_info *exec)
 					  sizeof(struct vc4_shader_state)) ||
 	    temp_size < exec_size) {
 		DRM_ERROR("overflow in exec arguments\n");
+		ret = -EINVAL;
 		goto fail;
 	}