2 files changed, 14 insertions, 0 deletions
diff --git a/llvm/lib/DebugInfo/MSF/MSFBuilder.cpp b/llvm/lib/DebugInfo/MSF/MSFBuilder.cpp
index f9a763d724a8..c26caa647ed9 100644
--- a/llvm/lib/DebugInfo/MSF/MSFBuilder.cpp
+++ b/llvm/lib/DebugInfo/MSF/MSFBuilder.cpp
@@ -364,6 +364,18 @@ Expected<FileBufferByteStream> MSFBuilder::commit(StringRef Path,
                 FileSize, Layout.SB->BlockSize));
   }
 
+  uint64_t NumDirectoryBlocks =
+      bytesToBlocks(Layout.SB->NumDirectoryBytes, Layout.SB->BlockSize);
+  uint64_t DirectoryBlockMapSize =
+      NumDirectoryBlocks * sizeof(support::ulittle32_t);
+  if (DirectoryBlockMapSize > Layout.SB->BlockSize) {
+    return make_error<MSFError>(msf_error_code::stream_directory_overflow,
+                                formatv("The directory block map ({0} bytes) "
+                                        "doesn't fit in a block ({1} bytes)",
+                                        DirectoryBlockMapSize,
+                                        Layout.SB->BlockSize));
+  }
+
   auto OutFileOrError = FileOutputBuffer::create(Path, FileSize);
   if (auto EC = OutFileOrError.takeError())
     return std::move(EC);
diff --git a/llvm/lib/DebugInfo/MSF/MSFError.cpp b/llvm/lib/DebugInfo/MSF/MSFError.cpp
index fd93c3e726cc..dbd8648c4d41 100644
--- a/llvm/lib/DebugInfo/MSF/MSFError.cpp
+++ b/llvm/lib/DebugInfo/MSF/MSFError.cpp
@@ -43,6 +43,8 @@ public:
       return "The data is in an unexpected format.";
     case msf_error_code::block_in_use:
       return "The block is already in use.";
+    case msf_error_code::stream_directory_overflow:
+      return "PDB stream directory too large.";
     }
     llvm_unreachable("Unrecognized msf_error_code");
   }