[dsymutil] Prevent use-after-free

The BinaryHolder would query the archive member MemoryBuffer name
to check if the current open archive also contains the next requested
objectfile. This comparison was using a StringRef to a temporary
buffer. It only happened with fat archives. This commit adds long-lived
storage along with the MemoryBuffers for the fat archive filename.

The added test would fail during an ASAN build without the fix.

llvm-svn: 268924

2 files changed, 5 insertions, 2 deletions

diff --git a/llvm/tools/dsymutil/BinaryHolder.cpp b/llvm/tools/dsymutil/BinaryHolder.cpp
index 7644f01952f..32d176645bf 100644
--- a/llvm/tools/dsymutil/BinaryHolder.cpp
+++ b/llvm/tools/dsymutil/BinaryHolder.cpp
@@ -79,7 +79,8 @@ BinaryHolder::GetMemoryBuffersForFile(StringRef Filename,
   }
 
   CurrentFatBinary = std::move(*ErrOrFat);
-  return getMachOFatMemoryBuffers(Filename, *CurrentMemoryBuffer,
+  CurrentFatBinaryName = Filename;
+  return getMachOFatMemoryBuffers(CurrentFatBinaryName, *CurrentMemoryBuffer,
                                   *CurrentFatBinary);
 }
 
@@ -149,8 +150,9 @@ BinaryHolder::MapArchiveAndGetMemberBuffers(StringRef Filename,
     ArchiveBuffers.push_back(CurrentMemoryBuffer->getMemBufferRef());
   } else {
     CurrentFatBinary = std::move(*ErrOrFat);
+    CurrentFatBinaryName = ArchiveFilename;
     ArchiveBuffers = getMachOFatMemoryBuffers(
-        ArchiveFilename, *CurrentMemoryBuffer, *CurrentFatBinary);
+        CurrentFatBinaryName, *CurrentMemoryBuffer, *CurrentFatBinary);
   }
 
   for (auto MemRef : ArchiveBuffers) {
diff --git a/llvm/tools/dsymutil/BinaryHolder.h b/llvm/tools/dsymutil/BinaryHolder.h
index d56a39597c2..97508b9fb09 100644
--- a/llvm/tools/dsymutil/BinaryHolder.h
+++ b/llvm/tools/dsymutil/BinaryHolder.h
@@ -42,6 +42,7 @@ class BinaryHolder {
   std::unique_ptr<MemoryBuffer> CurrentMemoryBuffer;
   std::vector<std::unique_ptr<object::ObjectFile>> CurrentObjectFiles;
   std::unique_ptr<object::MachOUniversalBinary> CurrentFatBinary;
+  std::string CurrentFatBinaryName;
   bool Verbose;
 
   /// Get the MemoryBufferRefs for the file specification in \p