[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, 6 insertions, 3 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp b/llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
index 859295d2c7d..1254e23c73e 100644
--- a/llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/PDBFile.cpp
@@ -146,7 +146,8 @@ Error PDBFile::parseFileHeaders() {
   // at getBlockSize() intervals, so we have to be compatible.
   // See the function fpmPn() for more information:
   // https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/msf/msf.cpp#L489
-  auto FpmStream = MappedBlockStream::createFpmStream(ContainerLayout, *Buffer);
+  auto FpmStream =
+      MappedBlockStream::createFpmStream(ContainerLayout, *Buffer, Allocator);
   BinaryStreamReader FpmReader(*FpmStream);
   ArrayRef<uint8_t> FpmBytes;
   if (auto EC = FpmReader.readBytes(FpmBytes,
@@ -184,7 +185,8 @@ Error PDBFile::parseStreamData() {
   // is exactly what we are attempting to parse.  By specifying a custom
   // subclass of IPDBStreamData which only accesses the fields that have already
   // been parsed, we can avoid this and reuse MappedBlockStream.
-  auto DS = MappedBlockStream::createDirectoryStream(ContainerLayout, *Buffer);
+  auto DS = MappedBlockStream::createDirectoryStream(ContainerLayout, *Buffer,
+                                                     Allocator);
   BinaryStreamReader Reader(*DS);
   if (auto EC = Reader.readInteger(NumStreams))
     return EC;
@@ -407,5 +409,6 @@ PDBFile::safelyCreateIndexedStream(const MSFLayout &Layout,
                                    uint32_t StreamIndex) const {
   if (StreamIndex >= getNumStreams())
     return make_error<RawError>(raw_error_code::no_stream);
-  return MappedBlockStream::createIndexedStream(Layout, MsfData, StreamIndex);
+  return MappedBlockStream::createIndexedStream(Layout, MsfData, StreamIndex,
+                                                Allocator);
 }