WebAssembly: skip unknown sections, add names

src/wasm/module-decoder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/macro-assembler.h"
 #include "src/objects.h"
 #include "src/v8.h"
 
 #include "src/wasm/decoder.h"
 #include "src/wasm/module-decoder.h"
@@ skipping 60 matching lines @@
       error(pos, pos,
             "expected version %02x %02x %02x %02x, "
             "found %02x %02x %02x %02x",
             BYTES(kWasmVersion), BYTES(magic_version));
       return toResult(module);
     }
 
     // Decode the module sections.
     while (pc_ < limit_) {
       TRACE("DecodeSection\n");
-      WasmSectionDeclCode section =
-          static_cast<WasmSectionDeclCode>(consume_u8("section"));
+      uint8_t section_u8 = consume_u8("section");
+
+      if (section_u8 >= kMaxModuleSectionCode) {
+        // Skip unknown section.
+        int length;
+        uint32_t section_bytes = consume_u32v(&length, "section size");
+        consume_bytes(section_bytes);
+        continue;
+      }
+
       // Each section should appear at most once.
-      if (section < kMaxModuleSectionCode) {
-        CheckForPreviousSection(sections, section, false);
-        sections[section] = true;
-      }
+      auto section = static_cast<WasmSectionDeclCode>(section_u8);
+      CheckForPreviousSection(sections, section, false);
+      sections[section] = true;
 
       switch (section) {
         case kDeclEnd:
           // Terminate section decoding.
           limit_ = pc_;
           break;
         case kDeclMemory:
           int length;
           module->min_mem_pages = consume_u32v(&length, "min memory");
           module->max_mem_pages = consume_u32v(&length, "max memory");
@@ skipping 174 matching lines @@
             if (exp->func_index >= module->functions.size()) {
               error(sigpos, sigpos,
                     "function index %u out of bounds (%d functions)",
                     exp->func_index,
                     static_cast<int>(module->functions.size()));
             }
             exp->name_offset = consume_string("export name");
           }
           break;
         }
-        case kDeclWLL: {
-          // Reserved for experimentation by the Web Low-level Language project
-          // which is augmenting the binary encoding with source code meta
-          // information. This section does not affect the semantics of the code
-          // and can be ignored by the runtime. https://github.com/JSStats/wll
-          int length = 0;
-          uint32_t section_size = consume_u32v(&length, "section size");
-          if (pc_ + section_size > limit_ || pc_ + section_size < pc_) {
-            error(pc_ - length, "invalid section size");
-            break;
-          }
-          pc_ += section_size;
-          break;
-        }
-        default:
-          error(pc_ - 1, nullptr, "unrecognized section 0x%02x", section);
-          break;
+        case kMaxModuleSectionCode:
+          UNREACHABLE();  // Already skipped unknown sections.
       }
     }
 
     return toResult(module);
   }
 
   uint32_t SafeReserve(uint32_t count) {
     // Avoid OOM by only reserving up to a certain size.
     const uint32_t kMaxReserve = 20000;
     return count < kMaxReserve ? count : kMaxReserve;
@@ skipping 343 matching lines @@
   if (function_start > function_end) return FunctionError("start > end");
   if (size > kMaxFunctionSize)
     return FunctionError("size > maximum function size");
   WasmFunction* function = new WasmFunction();
   ModuleDecoder decoder(zone, function_start, function_end, kWasmOrigin);
   return decoder.DecodeSingleFunction(module_env, function);
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8