Fix unnecessary failure when Crossgen'ing dll's without proper Debug Directory data

src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.cs

@@ -200,7 +200,8 @@ private EcmaModule AddModule(string filePath, string expectedSimpleName, bool us
                     throw new NotSupportedException($"Error: C++/CLI is not supported: '{filePath}'");
 #endif
 
-                    pdbReader = PortablePdbSymbolReader.TryOpenEmbedded(peReader, GetMetadataStringDecoder()) ?? OpenAssociatedSymbolFile(filePath, peReader);
+                    pdbReader = PortablePdbSymbolReader.TryOpenEmbedded(peReader, GetMetadataStringDecoder())
+                                ?? OpenAssociatedSymbolFile(filePath, peReader);
                 }
                 else
                 {
@@ -327,7 +328,7 @@ private PdbSymbolReader OpenAssociatedSymbolFile(string peFilePath, PEReader peR
             string pdbFileName = null;
             BlobContentId pdbContentId = default;
 
-            foreach (DebugDirectoryEntry debugEntry in peReader.ReadDebugDirectory())
+            foreach (DebugDirectoryEntry debugEntry in peReader.SafeReadDebugDirectory())
             {
                 if (debugEntry.Type != DebugDirectoryEntryType.CodeView)
                     continue;

src/coreclr/tools/Common/TypeSystem/Common/PortableExecutableMethodExtensions.cs

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Immutable;
+using System.Reflection.PortableExecutable;
+
+namespace Internal.TypeSystem
+{
+    public static class PortableExecutableMethodExtensions
+    {
+        public static ImmutableArray<DebugDirectoryEntry> SafeReadDebugDirectory(this PEReader peReader)
+        {
+            int actualDbgDirSize = peReader.PEHeaders.PEHeader.DebugTableDirectory.Size;
+
+            // This comes from the Size property of the DebugDirectoryEntry class.
+            const int expectedDbgDirSizeBase = 28;
+
+            if (actualDbgDirSize % expectedDbgDirSizeBase != 0)
+                return ImmutableArray<DebugDirectoryEntry>.Empty;
+
+            return peReader.ReadDebugDirectory();
+        }
+    }
+}

src/coreclr/tools/Common/TypeSystem/Ecma/SymbolReader/PortablePdbSymbolReader.cs

@@ -81,7 +81,7 @@ public static PdbSymbolReader TryOpen(string pdbFilename, MetadataStringDecoder
 
         public static PdbSymbolReader TryOpenEmbedded(PEReader peReader, MetadataStringDecoder stringDecoder)
         {
-            foreach (DebugDirectoryEntry debugEntry in peReader.ReadDebugDirectory())
+            foreach (DebugDirectoryEntry debugEntry in peReader.SafeReadDebugDirectory())
             {
                 if (debugEntry.Type != DebugDirectoryEntryType.EmbeddedPortablePdb)
                     continue;

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/DebugDirectoryEntryNode.cs

@@ -8,6 +8,7 @@
 using System.Reflection.PortableExecutable;
 
 using Internal.Text;
+using Internal.TypeSystem;
 using Internal.TypeSystem.Ecma;
 using System.IO;
 using System.Collections.Immutable;
@@ -250,7 +251,7 @@ public override ObjectData GetData(NodeFactory factory, bool relocsOnly = false)
                 return new ObjectData(Array.Empty<byte>(), Array.Empty<Relocation>(), 1, new ISymbolDefinitionNode[] { this });
             }
 
-            ImmutableArray<DebugDirectoryEntry> entries = _module.PEReader.ReadDebugDirectory();
+            ImmutableArray<DebugDirectoryEntry> entries = _module.PEReader.SafeReadDebugDirectory();
             Debug.Assert(entries != null && _debugEntryIndex < entries.Length);
 
             DebugDirectoryEntry sourceDebugEntry = entries[_debugEntryIndex];

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/DebugDirectoryNode.cs

@@ -88,7 +88,7 @@ int GetNumDebugDirectoryEntriesInModule()
             if (_module == null)
                 return 0;
 
-            ImmutableArray<DebugDirectoryEntry> entries = _module.PEReader.ReadDebugDirectory();
+            ImmutableArray<DebugDirectoryEntry> entries = _module.PEReader.SafeReadDebugDirectory();
             return entries == null ? 0 : entries.Length;
         }
 
@@ -99,8 +99,9 @@ public override ObjectData GetData(NodeFactory factory, bool relocsOnly = false)
             builder.AddSymbol(this);
 
             ImmutableArray<DebugDirectoryEntry> entries = ImmutableArray<DebugDirectoryEntry>.Empty;
+
             if (_module != null)
-                entries = _module.PEReader.ReadDebugDirectory();
+                entries = _module.PEReader.SafeReadDebugDirectory();
 
             int numEntries = GetNumDebugDirectoryEntriesInModule();
 

src/coreclr/tools/aot/ILCompiler.TypeSystem/ILCompiler.TypeSystem.csproj

@@ -31,6 +31,7 @@
       <Version>1.4.0</Version>
     </PackageReference>
   </ItemGroup>
+
   <ItemGroup>
     <Compile Include="..\..\Common\TypeSystem\Common\ArrayMethod.Diagnostic.cs">
       <Link>TypeSystem\Common\ArrayMethod.Diagnostic.cs</Link>
@@ -359,6 +360,9 @@
     <Compile Include="..\..\Common\TypeSystem\Common\RuntimeInterfacesAlgorithm.cs">
       <Link>TypeSystem\Common\RuntimeInterfacesAlgorithm.cs</Link>
     </Compile>
+    <Compile Include="..\..\Common\TypeSystem\Common\PortableExecutableMethodExtensions.cs">
+      <Link>Compiler\PortableExecutableMethodExtensions.cs</Link>
+    </Compile>
     <Compile Include="..\..\Common\TypeSystem\Ecma\CustomAttributeTypeProvider.cs">
       <Link>Ecma\CustomAttributeTypeProvider.cs</Link>
     </Compile>

src/coreclr/tools/dotnet-pgo/Program.cs

@@ -1299,7 +1299,7 @@ static int InnerProcessTraceFileMain(CommandLineOptions commandLineOptions)
                     bool matched = false;
                     bool mismatch = false;
                     bool mismatchHandled = false;
-                    foreach (var debugEntry in ecmaModule.PEReader.ReadDebugDirectory())
+                    foreach (DebugDirectoryEntry debugEntry in ecmaModule.PEReader.SafeReadDebugDirectory())
                     {
                         if (debugEntry.Type == DebugDirectoryEntryType.CodeView)
                         {

src/coreclr/tools/dotnet-pgo/TraceTypeSystemContext.cs

@@ -364,7 +364,7 @@ private PdbSymbolReader OpenAssociatedSymbolFile(string peFilePath, PEReader peR
             string pdbFileName = null;
             BlobContentId pdbContentId = default;
 
-            foreach (DebugDirectoryEntry debugEntry in peReader.ReadDebugDirectory())
+            foreach (DebugDirectoryEntry debugEntry in peReader.SafeReadDebugDirectory())
             {
                 if (debugEntry.Type != DebugDirectoryEntryType.CodeView)
                     continue;