drm/msm/adreno: Ensure that the zap shader region is big enough

Before loading the zap shader we should ensure that the reserved memory
region is big enough to hold the loaded file.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/adreno_gpu.c

@@ -67,7 +67,6 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname,
 		return ret;
 
 	mem_phys = r.start;
-	mem_size = resource_size(&r);
 
 	/* Request the MDT file for the firmware */
 	fw = adreno_request_fw(to_adreno_gpu(gpu), fwname);
@@ -83,6 +82,13 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname,
 		goto out;
 	}
 
+	if (mem_size > resource_size(&r)) {
+		DRM_DEV_ERROR(dev,
+			"memory region is too small to load the MDT\n");
+		ret = -E2BIG;
+		goto out;
+	}
+
 	/* Allocate memory for the firmware image */
 	mem_region = memremap(mem_phys, mem_size,  MEMREMAP_WC);
 	if (!mem_region) {