From b1f58bded0925343bd322f5ab60e4b1515f12cea Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan.enderlin@hoa-project.net>
Date: Thu, 21 Nov 2019 10:57:52 +0100
Subject: [PATCH] fix(runtime-core) Improve error message when globals are
 corrupted.

Before this patch:

```
$ cargo run -- run panic_index_oob_all_backends.wasm
Error: ExportNotFound { name: "main" }
```

With this patch:

```sh
$ cargo run -- run panic_index_oob_all_backends.wasm
Error: Can't instantiate module: LinkError([Generic { message: "Trying to read the `0` global that isn\'t properly initialized." }])
```
---
 lib/runtime-core/src/backing.rs | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/lib/runtime-core/src/backing.rs b/lib/runtime-core/src/backing.rs
index c3118cfb0..1b50abaf6 100644
--- a/lib/runtime-core/src/backing.rs
+++ b/lib/runtime-core/src/backing.rs
@@ -77,7 +77,7 @@ impl LocalBacking {
             }
         };
         let mut tables = Self::generate_tables(module);
-        let mut globals = Self::generate_globals(module, imports);
+        let mut globals = Self::generate_globals(module, imports)?;
 
         // Ensure all initializers are valid before running finalizers
         Self::validate_memories(module, imports)?;
@@ -443,16 +443,20 @@ impl LocalBacking {
     fn generate_globals(
         module: &ModuleInner,
         imports: &ImportBacking,
-    ) -> BoxedMap<LocalGlobalIndex, Global> {
+    ) -> LinkResult<BoxedMap<LocalGlobalIndex, Global>> {
         let mut globals = Map::with_capacity(module.info.globals.len());
 
         for (_, global_init) in module.info.globals.iter() {
             let value = match &global_init.init {
                 Initializer::Const(value) => value.clone(),
                 Initializer::GetGlobal(import_global_index) => {
-                    // Skip if the global hasn't been initialized properly.
                     if imports.globals.len() <= import_global_index.index() {
-                        continue;
+                        return Err(vec![LinkError::Generic {
+                            message: format!(
+                                "Trying to read the `{:?}` global that is not properly initialized.",
+                                import_global_index.index()
+                            ),
+                        }]);
                     }
 
                     imports.globals[*import_global_index].get()
@@ -468,7 +472,7 @@ impl LocalBacking {
             globals.push(global);
         }
 
-        globals.into_boxed_map()
+        Ok(globals.into_boxed_map())
     }
 
     fn finalize_globals(