From ed9e7f1ad033404901a231fb5840225bef137581 Mon Sep 17 00:00:00 2001
From: Ali Mohammad Pur <ali.mpfard@gmail.com>
Date: Thu, 9 Dec 2021 21:32:01 +0330
Subject: [PATCH] LibWasm: Tolerate modules with invalid sections and mark them
 as invalid

We should not crash, but rather just fail to verify them.
---
 Userland/Libraries/LibWasm/Parser/Parser.cpp | 13 ++++++++++---
 Userland/Libraries/LibWasm/Types.h           |  7 +++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibWasm/Parser/Parser.cpp b/Userland/Libraries/LibWasm/Parser/Parser.cpp
index d2ae4d4561..19558070c8 100644
--- a/Userland/Libraries/LibWasm/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWasm/Parser/Parser.cpp
@@ -1363,16 +1363,22 @@ ParseResult<Module> Module::parse(InputStream& stream)
     return Module { move(sections) };
 }
 
-void Module::populate_sections()
+bool Module::populate_sections()
 {
+    auto is_ok = true;
     FunctionSection const* function_section { nullptr };
     for_each_section_of_type<FunctionSection>([&](FunctionSection const& section) { function_section = &section; });
     for_each_section_of_type<CodeSection>([&](CodeSection const& section) {
-        // FIXME: This should be considered invalid once validation is implemented.
-        if (!function_section)
+        if (!function_section) {
+            is_ok = false;
             return;
+        }
         size_t index = 0;
         for (auto& entry : section.functions()) {
+            if (function_section->types().size() <= index) {
+                is_ok = false;
+                return;
+            }
             auto& type_index = function_section->types()[index];
             Vector<ValueType> locals;
             for (auto& local : entry.func().locals()) {
@@ -1383,6 +1389,7 @@ void Module::populate_sections()
             ++index;
         }
     });
+    return is_ok;
 }
 
 String parse_error_to_string(ParseError error)
diff --git a/Userland/Libraries/LibWasm/Types.h b/Userland/Libraries/LibWasm/Types.h
index 1332333271..4677be889c 100644
--- a/Userland/Libraries/LibWasm/Types.h
+++ b/Userland/Libraries/LibWasm/Types.h
@@ -1003,7 +1003,10 @@ public:
     explicit Module(Vector<AnySection> sections)
         : m_sections(move(sections))
     {
-        populate_sections();
+        if (!populate_sections()) {
+            m_validation_status = ValidationStatus::Invalid;
+            m_validation_error = "Failed to populate module sections"sv;
+        }
     }
 
     auto& sections() const { return m_sections; }
@@ -1044,7 +1047,7 @@ public:
     static ParseResult<Module> parse(InputStream& stream);
 
 private:
-    void populate_sections();
+    bool populate_sections();
     void set_validation_status(ValidationStatus status) { m_validation_status = status; }
 
     Vector<AnySection> m_sections;