[PDB] Fix use after free.

Previously MappedBlockStream owned its own BumpPtrAllocator that
it would allocate from when a read crossed a block boundary.  This
way it could still return the user a contiguous buffer of the
requested size.  However, It's not uncommon to open a stream, read
some stuff, close it, and then save the information for later.
After all, since the entire file is mapped into memory, the data
should always be available as long as the file is open.

Of course, the exception to this is when the data isn't *in* the
file, but rather in some buffer that we temporarily allocated to
present this contiguous view.  And this buffer would get destroyed
as soon as the strema was closed.

The fix here is to force the user to specify the allocator, this
way it can provide an allocator that has whatever lifetime it
chooses.

Differential Revision: https://reviews.llvm.org/D33858

llvm-svn: 304623

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp b/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
index c656802..2c6465e 100644
--- a/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp
@@ -140,8 +140,8 @@ Error PDBFileBuilder::commit(StringRef Filename) {
   if (auto EC = Writer.writeArray(Layout.DirectoryBlocks))
     return EC;
 
-  auto DirStream =
-      WritableMappedBlockStream::createDirectoryStream(Layout, Buffer);
+  auto DirStream = WritableMappedBlockStream::createDirectoryStream(
+      Layout, Buffer, Allocator);
   BinaryStreamWriter DW(*DirStream);
   if (auto EC = DW.writeInteger<uint32_t>(Layout.StreamSizes.size()))
     return EC;
@@ -158,8 +158,8 @@ Error PDBFileBuilder::commit(StringRef Filename) {
   if (!ExpectedSN)
     return ExpectedSN.takeError();
 
-  auto NS = WritableMappedBlockStream::createIndexedStream(Layout, Buffer,
-                                                           *ExpectedSN);
+  auto NS = WritableMappedBlockStream::createIndexedStream(
+      Layout, Buffer, *ExpectedSN, Allocator);
   BinaryStreamWriter NSWriter(*NS);
   if (auto EC = Strings.commit(NSWriter))
     return EC;