[wasm] Support for restricted table imports.

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/wasm/module-decoder.h"
 
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/flags.h"
 #include "src/macro-assembler.h"
@@ skipping 13 matching lines @@
   } while (false)
 #else
 #define TRACE(...)
 #endif
 
 namespace {
 
 const char* kNameString = "name";
 const size_t kNameStringLength = 4;
 
-static const uint32_t kMaxTableSize = 1 << 28;
-
 LocalType TypeOf(const WasmModule* module, const WasmInitExpr& expr) {
   switch (expr.kind) {
     case WasmInitExpr::kNone:
       return kAstStmt;
     case WasmInitExpr::kGlobalIndex:
       return expr.val.global_index < module->globals.size()
                  ? module->globals[expr.val.global_index].type
                  : kAstStmt;
     case WasmInitExpr::kI32Const:
       return kAstI32;
@@ skipping 258 matching lines @@
                                          true,           // imported
                                          false});        // exported
             WasmFunction* function = &module->functions.back();
             function->sig_index = consume_sig_index(module, &function->sig);
             break;
           }
           case kExternalTable: {
             // ===== Imported table ==========================================
             import->index =
                 static_cast<uint32_t>(module->function_tables.size());
-            module->function_tables.push_back(
-                {0, 0, std::vector<int32_t>(), true, false, SignatureMap()});
+            module->function_tables.push_back({0, 0, false,
+                                               std::vector<int32_t>(), true,
+                                               false, SignatureMap()});
             expect_u8("element type", kWasmAnyFunctionTypeForm);
             WasmIndirectFunctionTable* table = &module->function_tables.back();
-            consume_resizable_limits("element count", "elements", kMaxTableSize,
-                                     &table->size, &table->max_size);
+            consume_resizable_limits(
+                "element count", "elements", WasmModule::kV8MaxTableSize,
+                &table->min_size, &table->has_max, &table->max_size);
             break;
           }
           case kExternalMemory: {
             // ===== Imported memory =========================================
-            consume_resizable_limits(
-                "memory", "pages", WasmModule::kMaxLegalPages,
-                &module->min_mem_pages, &module->max_mem_pages);
+            bool has_max = false;
+            consume_resizable_limits("memory", "pages", WasmModule::kV8MaxPages,
+                                     &module->min_mem_pages, &has_max,
+                                     &module->max_mem_pages);
             break;
           }
           case kExternalGlobal: {
             // ===== Imported global =========================================
             import->index = static_cast<uint32_t>(module->globals.size());
             module->globals.push_back(
                 {kAstStmt, false, WasmInitExpr(), 0, true, false});
             WasmGlobal* global = &module->globals.back();
             global->type = consume_value_type();
             global->mutability = consume_u8("mutability") != 0;
@@ skipping 31 matching lines @@
 
     // ===== Table section ===================================================
     if (section_iter.section_code() == kTableSectionCode) {
       const byte* pos = pc_;
       uint32_t table_count = consume_u32v("table count");
       // Require at most one table for now.
       if (table_count > 1) {
         error(pos, pos, "invalid table count %d, maximum 1", table_count);
       }
       if (module->function_tables.size() < 1) {
-        module->function_tables.push_back(
-            {0, 0, std::vector<int32_t>(), false, false, SignatureMap()});
+        module->function_tables.push_back({0, 0, false, std::vector<int32_t>(),
+                                           false, false, SignatureMap()});
       }
 
       for (uint32_t i = 0; ok() && i < table_count; i++) {
         WasmIndirectFunctionTable* table = &module->function_tables.back();
         expect_u8("table type", kWasmAnyFunctionTypeForm);
-        consume_resizable_limits("table elements", "elements", kMaxUInt32,
-                                 &table->size, &table->max_size);
+        consume_resizable_limits("table elements", "elements",
+                                 WasmModule::kV8MaxTableSize, &table->min_size,
+                                 &table->has_max, &table->max_size);
       }
       section_iter.advance();
     }
 
     // ===== Memory section ==================================================
     if (section_iter.section_code() == kMemorySectionCode) {
       const byte* pos = pc_;
       uint32_t memory_count = consume_u32v("memory count");
       // Require at most one memory for now.
       if (memory_count > 1) {
         error(pos, pos, "invalid memory count %d, maximum 1", memory_count);
       }
 
       for (uint32_t i = 0; ok() && i < memory_count; i++) {
-        consume_resizable_limits("memory", "pages", WasmModule::kMaxLegalPages,
-                                 &module->min_mem_pages,
+        bool has_max = false;
+        consume_resizable_limits("memory", "pages", WasmModule::kV8MaxPages,
+                                 &module->min_mem_pages, &has_max,
                                  &module->max_mem_pages);
       }
       section_iter.advance();
     }
 
     // ===== Global section ==================================================
     if (section_iter.section_code() == kGlobalSectionCode) {
       uint32_t globals_count = consume_u32v("globals count");
       uint32_t imported_globals = static_cast<uint32_t>(module->globals.size());
       if (!IsWithinLimit(std::numeric_limits<int32_t>::max(), globals_count,
@@ skipping 201 matching lines @@
     }
 
     // ===== Remaining sections ==============================================
     if (section_iter.more() && ok()) {
       error(pc(), pc(), "unexpected section: %s",
             SectionName(section_iter.section_code()));
     }
 
     if (ok()) {
       CalculateGlobalOffsets(module);
-      PreinitializeIndirectFunctionTables(module);
     }
     const WasmModule* finished_module = module;
     ModuleResult result = toResult(finished_module);
     if (FLAG_dump_wasm_module) DumpModule(module, result);
     return result;
   }
 
   uint32_t SafeReserve(uint32_t count) {
     // Avoid OOM by only reserving up to a certain size.
     const uint32_t kMaxReserve = 20000;
@@ skipping 105 matching lines @@
     for (WasmGlobal& global : module->globals) {
       byte size =
           WasmOpcodes::MemSize(WasmOpcodes::MachineTypeFor(global.type));
       offset = (offset + size - 1) & ~(size - 1);  // align
       global.offset = offset;
       offset += size;
     }
     module->globals_size = offset;
   }
 
-  // TODO(titzer): this only works without overlapping initializations from
-  // global bases for entries
-  void PreinitializeIndirectFunctionTables(WasmModule* module) {
-    // Fill all tables with invalid entries first.
-    for (WasmIndirectFunctionTable& table : module->function_tables) {
-      table.values.resize(table.size);
-      for (size_t i = 0; i < table.size; i++) {
-        table.values[i] = kInvalidFunctionIndex;
-      }
-    }
-    for (WasmTableInit& init : module->table_inits) {
-      if (init.offset.kind != WasmInitExpr::kI32Const) continue;
-      if (init.table_index >= module->function_tables.size()) continue;
-      WasmIndirectFunctionTable& table =
-          module->function_tables[init.table_index];
-      for (size_t i = 0; i < init.entries.size(); i++) {
-        size_t index = i + init.offset.val.i32_const;
-        if (index < table.values.size()) {
-          table.values[index] = init.entries[i];
-        }
-      }
-    }
-  }
-
   // Verifies the body (code) of a given function.
   void VerifyFunctionBody(uint32_t func_num, ModuleEnv* menv,
                           WasmFunction* function) {
     if (FLAG_trace_wasm_decoder || FLAG_trace_wasm_decode_time) {
       OFStream os(stdout);
       os << "Verifying WASM function " << WasmFunctionName(function, menv)
          << std::endl;
     }
     FunctionBody body = {menv, function->sig, start_,
                          start_ + function->code_start_offset,
@@ skipping 73 matching lines @@
             static_cast<int>(vector.size()));
       *ptr = nullptr;
       return 0;
     }
     *ptr = &vector[index];
     return index;
   }
 
   void consume_resizable_limits(const char* name, const char* units,
                                 uint32_t max_value, uint32_t* initial,
-                                uint32_t* maximum) {
+                                bool* has_max, uint32_t* maximum) {
     uint32_t flags = consume_u32v("resizable limits flags");
     const byte* pos = pc();
     *initial = consume_u32v("initial size");
+    *has_max = false;
     if (*initial > max_value) {
       error(pos, pos,
-            "initial %s size (%u %s) is larger than maximum allowable (%u)",
+            "initial %s size (%u %s) is larger than implementation limit (%u)",
             name, *initial, units, max_value);
     }
     if (flags & 1) {
+      *has_max = true;
       pos = pc();
       *maximum = consume_u32v("maximum size");
       if (*maximum > max_value) {
-        error(pos, pos,
-              "maximum %s size (%u %s) is larger than maximum allowable (%u)",
-              name, *maximum, units, max_value);
+        error(
+            pos, pos,
+            "maximum %s size (%u %s) is larger than implementation limit (%u)",
+            name, *maximum, units, max_value);
       }
       if (*maximum < *initial) {
         error(pos, pos, "maximum %s size (%u %s) is less than initial (%u %s)",
               name, *maximum, units, *initial, units);
       }
     } else {
-      *maximum = 0;
+      *has_max = false;
+      *maximum = max_value;
     }
   }
 
   bool expect_u8(const char* name, uint8_t expected) {
     const byte* pos = pc();
     uint8_t value = consume_u8(name);
     if (value != expected) {
       error(pos, pos, "expected %s 0x%02x, got 0x%02x", name, expected, value);
       return false;
     }
@@ skipping 312 matching lines @@
     table.push_back(std::move(func_asm_offsets));
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8