Fix Wasm signature verification on big-endian platforms. (#241)

Signed-off-by: Piotr Sikora <[email protected]>

Author: PiotrSikora

.github/workflows/cpp.yml

@@ -109,7 +109,7 @@ jobs:
           repo: 'com_github_bytecodealliance_wasmtime'
           os: ubuntu-20.04
           arch: s390x
-          action: build
+          action: test
           run_under: docker run --rm --env HOME=$HOME --env USER=$(id -un) --volume "$HOME:$HOME" --workdir $(pwd) --user $(id -u):$(id -g) --platform linux/s390x piotrsikora/build-tools:bazel-5.0.0-clang-13-gcc-11
         - name: 'Wasmtime on macOS/x86_64'
           runtime: 'wasmtime'

src/signature_util.cc

@@ -85,6 +85,7 @@ bool SignatureUtil::verifySignature(std::string_view bytecode, std::string &mess
 
   uint32_t alg_id;
   std::memcpy(&alg_id, payload.data(), sizeof(uint32_t));
+  alg_id = le32toh(alg_id);
 
   if (alg_id != 2) {
     message = "Signature has a wrong alg_id (want: 2, is: " + std::to_string(alg_id) + ")";