[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, 34 insertions, 29 deletions

diff --git a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
index dfdeb841421..faf2442bc94 100644
--- a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
+++ b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
@@ -47,42 +47,46 @@ static Interval intersect(const Interval &I1, const Interval &I2) {
 
 MappedBlockStream::MappedBlockStream(uint32_t BlockSize,
                                      const MSFStreamLayout &Layout,
-                                     BinaryStreamRef MsfData)
-    : BlockSize(BlockSize), StreamLayout(Layout), MsfData(MsfData) {}
-
-std::unique_ptr<MappedBlockStream>
-MappedBlockStream::createStream(uint32_t BlockSize,
-                                const MSFStreamLayout &Layout,
-                                BinaryStreamRef MsfData) {
+                                     BinaryStreamRef MsfData,
+                                     BumpPtrAllocator &Allocator)
+    : BlockSize(BlockSize), StreamLayout(Layout), MsfData(MsfData),
+      Allocator(Allocator) {}
+
+std::unique_ptr<MappedBlockStream> MappedBlockStream::createStream(
+    uint32_t BlockSize, const MSFStreamLayout &Layout, BinaryStreamRef MsfData,
+    BumpPtrAllocator &Allocator) {
   return llvm::make_unique<MappedBlockStreamImpl<MappedBlockStream>>(
-      BlockSize, Layout, MsfData);
+      BlockSize, Layout, MsfData, Allocator);
 }
 
 std::unique_ptr<MappedBlockStream> MappedBlockStream::createIndexedStream(
-    const MSFLayout &Layout, BinaryStreamRef MsfData, uint32_t StreamIndex) {
+    const MSFLayout &Layout, BinaryStreamRef MsfData, uint32_t StreamIndex,
+    BumpPtrAllocator &Allocator) {
   assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
   SL.Blocks = Layout.StreamMap[StreamIndex];
   SL.Length = Layout.StreamSizes[StreamIndex];
   return llvm::make_unique<MappedBlockStreamImpl<MappedBlockStream>>(
-      Layout.SB->BlockSize, SL, MsfData);
+      Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createDirectoryStream(const MSFLayout &Layout,
-                                         BinaryStreamRef MsfData) {
+                                         BinaryStreamRef MsfData,
+                                         BumpPtrAllocator &Allocator) {
   MSFStreamLayout SL;
   SL.Blocks = Layout.DirectoryBlocks;
   SL.Length = Layout.SB->NumDirectoryBytes;
-  return createStream(Layout.SB->BlockSize, SL, MsfData);
+  return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createFpmStream(const MSFLayout &Layout,
-                                   BinaryStreamRef MsfData) {
+                                   BinaryStreamRef MsfData,
+                                   BumpPtrAllocator &Allocator) {
   MSFStreamLayout SL;
   initializeFpmStreamLayout(Layout, SL);
-  return createStream(Layout.SB->BlockSize, SL, MsfData);
+  return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 Error MappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
@@ -148,7 +152,7 @@ Error MappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
   // into it, and return an ArrayRef to that.  Do not touch existing pool
   // allocations, as existing clients may be holding a pointer which must
   // not be invalidated.
-  uint8_t *WriteBuffer = static_cast<uint8_t *>(Pool.Allocate(Size, 8));
+  uint8_t *WriteBuffer = static_cast<uint8_t *>(Allocator.Allocate(Size, 8));
   if (auto EC = readBytes(Offset, MutableArrayRef<uint8_t>(WriteBuffer, Size)))
     return EC;
 
@@ -269,10 +273,6 @@ Error MappedBlockStream::readBytes(uint32_t Offset,
   return Error::success();
 }
 
-uint32_t MappedBlockStream::getNumBytesCopied() const {
-  return static_cast<uint32_t>(Pool.getBytesAllocated());
-}
-
 void MappedBlockStream::invalidateCache() { CacheMap.shrink_and_clear(); }
 
 void MappedBlockStream::fixCacheAfterWrite(uint32_t Offset,
@@ -313,43 +313,48 @@ void MappedBlockStream::fixCacheAfterWrite(uint32_t Offset,
 
 WritableMappedBlockStream::WritableMappedBlockStream(
     uint32_t BlockSize, const MSFStreamLayout &Layout,
-    WritableBinaryStreamRef MsfData)
-    : ReadInterface(BlockSize, Layout, MsfData), WriteInterface(MsfData) {}
+    WritableBinaryStreamRef MsfData, BumpPtrAllocator &Allocator)
+    : ReadInterface(BlockSize, Layout, MsfData, Allocator),
+      WriteInterface(MsfData) {}
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createStream(uint32_t BlockSize,
                                         const MSFStreamLayout &Layout,
-                                        WritableBinaryStreamRef MsfData) {
+                                        WritableBinaryStreamRef MsfData,
+                                        BumpPtrAllocator &Allocator) {
   return llvm::make_unique<MappedBlockStreamImpl<WritableMappedBlockStream>>(
-      BlockSize, Layout, MsfData);
+      BlockSize, Layout, MsfData, Allocator);
 }
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createIndexedStream(const MSFLayout &Layout,
                                                WritableBinaryStreamRef MsfData,
-                                               uint32_t StreamIndex) {
+                                               uint32_t StreamIndex,
+                                               BumpPtrAllocator &Allocator) {
   assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
   SL.Blocks = Layout.StreamMap[StreamIndex];
   SL.Length = Layout.StreamSizes[StreamIndex];
-  return createStream(Layout.SB->BlockSize, SL, MsfData);
+  return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createDirectoryStream(
-    const MSFLayout &Layout, WritableBinaryStreamRef MsfData) {
+    const MSFLayout &Layout, WritableBinaryStreamRef MsfData,
+    BumpPtrAllocator &Allocator) {
   MSFStreamLayout SL;
   SL.Blocks = Layout.DirectoryBlocks;
   SL.Length = Layout.SB->NumDirectoryBytes;
-  return createStream(Layout.SB->BlockSize, SL, MsfData);
+  return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createFpmStream(const MSFLayout &Layout,
-                                           WritableBinaryStreamRef MsfData) {
+                                           WritableBinaryStreamRef MsfData,
+                                           BumpPtrAllocator &Allocator) {
   MSFStreamLayout SL;
   initializeFpmStreamLayout(Layout, SL);
-  return createStream(Layout.SB->BlockSize, SL, MsfData);
+  return createStream(Layout.SB->BlockSize, SL, MsfData, Allocator);
 }
 
 Error WritableMappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,