[wasm] Fix check failure on invalid name section

src/wasm/module-decoder.cc

Index: src/wasm/module-decoder.cc
diff --git a/src/wasm/module-decoder.cc b/src/wasm/module-decoder.cc
index 2a4752e0f6f5771c32bdb798bed18af1bea4e04b..39ecc422a8f145e4e3c22c41d8bd93b9a6840355 100644
--- a/src/wasm/module-decoder.cc
+++ b/src/wasm/module-decoder.cc
@@ -620,7 +620,7 @@ class ModuleDecoder : public Decoder {
         uint32_t name_offset =
             consume_string(inner, &function_name_length, false);
         uint32_t func_index = i;
-        if (func_index < module->functions.size()) {
+        if (inner.ok() && func_index < module->functions.size()) {

[bradn, 2017/01/25 11:18:05]

Ah I see.
Kind of goofy how this section is speced (i.e. can fail to validate but is still
ok).
Don't we need to back this out in the case that some later part of this section
fails?
I.e. we could end up with some names added but then fall over?

[titzer, 2017/01/25 11:53:29]

I'm OK with "best effort" if we just leave the names that did parse
successfully. I'm also OK clearing them, as it is probably just a simple loop
after this. But land away.

[Mircea Trofin, 2017/01/25 15:58:51]

We should take a stance though and propose a PR on the Spec. 

[Mircea Trofin, 2017/01/25 16:42:00]

Followed up with this PR, please take a look (includes a proposal for expected
behavior surrounding this section):

https://github.com/WebAssembly/design/pull/967/commits/c7ac091c4ab5488fe989d2...

           module->functions[func_index].name_offset = name_offset;
           module->functions[func_index].name_length = function_name_length;
         }