Index: llvm/trunk/include/llvm/Object/Wasm.h
===================================================================
--- llvm/trunk/include/llvm/Object/Wasm.h
+++ llvm/trunk/include/llvm/Object/Wasm.h
@@ -203,7 +203,9 @@
   bool isDefinedFunctionIndex(uint32_t Index) const;
   bool isValidGlobalIndex(uint32_t Index) const;
   bool isDefinedGlobalIndex(uint32_t Index) const;
-  bool isValidFunctionSymbolIndex(uint32_t Index) const;
+  bool isValidFunctionSymbol(uint32_t Index) const;
+  bool isValidGlobalSymbol(uint32_t Index) const;
+  bool isValidDataSymbol(uint32_t Index) const;
   wasm::WasmFunction &getDefinedFunction(uint32_t Index);
   wasm::WasmGlobal &getDefinedGlobal(uint32_t Index);
 
Index: llvm/trunk/lib/Object/WasmObjectFile.cpp
===================================================================
--- llvm/trunk/lib/Object/WasmObjectFile.cpp
+++ llvm/trunk/lib/Object/WasmObjectFile.cpp
@@ -339,7 +339,7 @@
         wasm::WasmInitFunc Init;
         Init.Priority = readVaruint32(Ptr);
         Init.Symbol = readVaruint32(Ptr);
-        if (!isValidFunctionSymbolIndex(Init.Symbol))
+        if (!isValidFunctionSymbol(Init.Symbol))
           return make_error<GenericBinaryError>("Invalid function symbol: " +
                                                     Twine(Init.Symbol),
                                                 object_error::parse_failed);
@@ -554,9 +554,10 @@
     return make_error<GenericBinaryError>("Invalid section code",
                                           object_error::parse_failed);
   uint32_t RelocCount = readVaruint32(Ptr);
+  uint32_t LastOffset = 0;
+  uint32_t EndOffset = Section->Content.size();
   while (RelocCount--) {
-    wasm::WasmRelocation Reloc;
-    memset(&Reloc, 0, sizeof(Reloc));
+    wasm::WasmRelocation Reloc = {};
     Reloc.Type = readVaruint32(Ptr);
     Reloc.Offset = readVaruint32(Ptr);
     Reloc.Index = readVaruint32(Ptr);
@@ -564,12 +565,26 @@
     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
+      if (!isValidFunctionSymbol(Reloc.Index))
+        return make_error<GenericBinaryError>("Bad relocation function index",
+                                              object_error::parse_failed);
+      break;
     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
+      if (Reloc.Index >= Signatures.size())
+        return make_error<GenericBinaryError>("Bad relocation type index",
+                                              object_error::parse_failed);
+      break;
     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
+      if (!isValidGlobalSymbol(Reloc.Index))
+        return make_error<GenericBinaryError>("Bad relocation global index",
+                                              object_error::parse_failed);
       break;
     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
+      if (!isValidDataSymbol(Reloc.Index))
+        return make_error<GenericBinaryError>("Bad relocation data index",
+                                              object_error::parse_failed);
       Reloc.Addend = readVarint32(Ptr);
       break;
     default:
@@ -577,6 +592,19 @@
                                                 Twine(Reloc.Type),
                                             object_error::parse_failed);
     }
+
+    // Relocations must fit inside the section, and must appear in order.  They
+    // also shouldn't overlap a function/element boundary, but we don't bother
+    // to check that.
+    uint64_t Size = 5;
+    if (Reloc.Type == wasm::R_WEBASSEMBLY_TABLE_INDEX_I32 ||
+        Reloc.Type == wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32)
+      Size = 4;
+    if (Reloc.Offset < LastOffset || Reloc.Offset + Size > EndOffset)
+      return make_error<GenericBinaryError>("Bad relocation offset",
+                                            object_error::parse_failed);
+    LastOffset = Reloc.Offset;
+
     Section->Relocations.push_back(Reloc);
   }
   if (Ptr != End)
@@ -787,10 +815,18 @@
   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
 }
 
-bool WasmObjectFile::isValidFunctionSymbolIndex(uint32_t Index) const {
+bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
 }
 
+bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
+  return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
+}
+
+bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
+  return Index < Symbols.size() && Symbols[Index].isTypeData();
+}
+
 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
   assert(isDefinedFunctionIndex(Index));
   return Functions[Index - NumImportedFunctions];
Index: llvm/trunk/test/ObjectYAML/wasm/code_section.yaml
===================================================================
--- llvm/trunk/test/ObjectYAML/wasm/code_section.yaml
+++ llvm/trunk/test/ObjectYAML/wasm/code_section.yaml
@@ -37,6 +37,19 @@
          - Type:            I32
            Count:           1
         Body:            108180808000210020000F0B
+  - Type:            CUSTOM
+    Name:            linking
+    SymbolTable:
+      - Index:           0
+        Kind:            FUNCTION
+        Name:            func1
+        Flags:           [  ]
+        Function:        0
+      - Index:           1
+        Kind:            FUNCTION
+        Name:            func2
+        Flags:           [  ]
+        Function:        1
 ...
 # CHECK: --- !WASM
 # CHECK: FileHeader:
Index: llvm/trunk/test/ObjectYAML/wasm/data_section.yaml
===================================================================
--- llvm/trunk/test/ObjectYAML/wasm/data_section.yaml
+++ llvm/trunk/test/ObjectYAML/wasm/data_section.yaml
@@ -22,6 +22,16 @@
         Index:           0
         Offset:          0x00000006
         Addend:          -6
+  - Type:            CUSTOM
+    Name:            linking
+    SymbolTable:
+      - Index:           0
+        Kind:            DATA
+        Name:            dataSymbol
+        Flags:           [  ]
+        Segment:         0
+        Offset:          0
+        Size:            4
 ...
 # CHECK: --- !WASM
 # CHECK: FileHeader:
@@ -44,4 +54,4 @@
 # CHECK-NEXT:           Opcode:          I32_CONST
 # CHECK-NEXT:           Value:           4
 # CHECK-NEXT:         Content:         '10001000'
-# CHECK-NEXT: ...
+# CHECK-NEXT:   - Type:            CUSTOM