From 175f2a6a6cabbfb9498dab82b27e45e54438a5d1 Mon Sep 17 00:00:00 2001
From: Stephan Herhut <herhut@chromium.org>
Date: Tue, 4 Sep 2018 11:52:14 +0200
Subject: [PATCH] [wasm] Throw a RuntimeError if memory lacks guard regions

WebAssembly.Instantiate would silently fail when the passed in memory
object did not have guard regions even though the compiled module assumes
so. This lead to an inconsitent state and a DCHECK error. Instead, now
throw a LinkError.

Change-Id: I68bab842bcc40d3325aea4b19979d80054ed407c
Reviewed-on: https://chromium-review.googlesource.com/1180892
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55601}
---
 src/wasm/module-compiler.cc | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/wasm/module-compiler.cc b/src/wasm/module-compiler.cc
index 4a6bab6250..7599f7828d 100644
--- a/src/wasm/module-compiler.cc
+++ b/src/wasm/module-compiler.cc
@@ -1015,6 +1015,9 @@ MaybeHandle<WasmInstanceObject> InstanceBuilder::Build() {
     if (!memory_tracker->HasFullGuardRegions(
             memory_.ToHandleChecked()->backing_store())) {
       if (!FLAG_wasm_trap_handler_fallback) {
+        thrower_->LinkError(
+            "Provided memory is lacking guard regions but fallback was "
+            "disabled.");
         return {};
       }