From c5f0cd7d5e350afe4dd2d18e8efc009ad7f1eae3 Mon Sep 17 00:00:00 2001
From: Dan Gohman <sunfish@mozilla.com>
Date: Tue, 28 Aug 2018 16:51:05 -0700
Subject: [PATCH] Enforce the wasm memory size limit on heaps with no maximum.

---
 lib/execute/src/memory.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/execute/src/memory.rs b/lib/execute/src/memory.rs
index 10069d95b3..4830b93861 100644
--- a/lib/execute/src/memory.rs
+++ b/lib/execute/src/memory.rs
@@ -57,6 +57,13 @@ impl LinearMemory {
             if new_pages > val {
                 return None;
             }
+        } else {
+            // Wasm linear memories are never allowed to grow beyond what is
+            // indexable. If the memory has no maximum, enforce the greatest
+            // limit here.
+            if new_pages >= 65536 {
+                return None;
+            }
         }
 
         let prev_pages = self.current;