Merge #995

995: fix(runtime-core) Remove a panic when generating globals with a corrupted module r=syrusakbary a=Hywan Fix #979. When we try to get a global that doesn't exist, a panic is generated. This patch skips such panic and let a proper error be generated. 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." }]) ``` Co-authored-by: Ivan Enderlin <[email protected]>
wasmerio · Nov 21, 2019 · d5f25aa · d5f25aa
2 parents 5e728ae + 7313672
commit d5f25aa
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## **[Unreleased]**
 
+- [#995](https://github.com/wasmerio/wasmer/pull/995) Detect when a global is read without being initialized (emit a proper error instead of panicking)
 - [#992](https://github.com/wasmerio/wasmer/pull/992) Updates WAPM version to 0.4.1, fix arguments issue introduced in #990
 - [#990](https://github.com/wasmerio/wasmer/pull/990) Default wasmer CLI to `run`.  Wasmer will now attempt to parse unrecognized command line options as if they were applied to the run command: `wasmer mywasm.wasm --dir=.` now works!
 - [#987](https://github.com/wasmerio/wasmer/pull/987) Fix `runtime-c-api` header files when compiled by gnuc.

diff --git 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)?;
@@ -443,13 +443,22 @@ 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) => {
+                    if imports.globals.len() <= import_global_index.index() {
+                        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()
                 }
             };
@@ -463,7 +472,7 @@ impl LocalBacking {
             globals.push(global);
         }
 
-        globals.into_boxed_map()
+        Ok(globals.into_boxed_map())
     }
 
     fn finalize_globals(