minus one

Author: sbc100

emcc.py

@@ -2188,8 +2188,8 @@ def check_memory_setting(setting):
     # Increase the minimum memory requirements to account for extra memory
     # that the sanitizers might need (in addition to the shadow memory
     # requirements handled below).
-    # These values are designed be over-estimate the actual requirements and
-    # based on experimentation with different tests/programs under asan and
+    # These values are designed be an over-estimate of the actual requirements and
+    # are based on experimentation with different tests/programs under asan and
     # lsan.
     settings.INITIAL_MEMORY += 50 * 1024 * 1024
     if settings.USE_PTHREADS:
@@ -2270,7 +2270,7 @@ def check_memory_setting(setting):
 
     # We start our global data after the shadow memory.
     # We don't need to worry about alignment here.  wasm-ld will take care of that.
-    settings.GLOBAL_BASE = shadow_size + 1
+    settings.GLOBAL_BASE = shadow_size
 
     if not settings.ALLOW_MEMORY_GROWTH:
       settings.INITIAL_MEMORY = total_mem

system/lib/compiler-rt/lib/asan/asan_emscripten.cpp

@@ -24,7 +24,7 @@ void InitializeShadowMemory() {
   // Assert that the shadow region is large enough.  We don't want to start
   // running into the static data region which starts right after the shadow
   // region.
-  uptr max_address = __builtin_wasm_memory_size(0) * WASM_PAGE_SIZE;
+  uptr max_address = (__builtin_wasm_memory_size(0) * WASM_PAGE_SIZE) - 1;
   uptr max_shadow_address = MEM_TO_SHADOW(max_address);
   // TODO(sbc): In the growable memory case we should really be checking this
   // every time we grow.