Add fuzzing helper scripts, fix fuzzing bugs (#416)

* Add fuzzing helper scripts, fix fuzzing bugs

The fuzzing dictionary was old, so I updated it. Also, I've added some
simple fuzzing shell scripts that make it a bit easier to run.

Bug fixes:

* Validate function index in local name section before calling callback.
* Fix invalid assert in parse_{float,double}_infinity, which assumed
  that "infinity" is required (it could be "inf").
* Bail out of resolve local names if there is no current function (e.g.
  if attempting to resolve names in an elem offset expression).
* Catch bad_alloc in wast2wasm and wasm2wast. Without this, afl-fuzz
  will see allocation failure as a crash.

* disable exceptions by default, add option, wrap tools in try/catch

1 files changed, 2 insertions, 0 deletions

diff --git a/src/binary-reader.cc b/src/binary-reader.cc
index 778c1ed6..4425f6ea 100644
--- a/src/binary-reader.cc
+++ b/src/binary-reader.cc
@@ -950,6 +950,8 @@ static void read_names_section(Context* ctx, uint32_t section_size) {
         for (uint32_t j = 0; j < num_funcs; ++j) {
           uint32_t function_index;
           in_u32_leb128(ctx, &function_index, "function index");
+          RAISE_ERROR_UNLESS(function_index < num_total_funcs(ctx),
+                             "invalid function index: %u", function_index);
           uint32_t num_locals;
           in_u32_leb128(ctx, &num_locals, "local count");
           CALLBACK(OnLocalNameLocalCount, function_index, num_locals);