[sanitizer] Re-introduce kUseSeparateSizeClassForBatch for the 32-bit Primary

Summary:
Currently `TransferBatch` are located within the same memory regions as
"regular" chunks. This is not ideal for security: they make for an interesting
target to overwrite, and are not protected by the frontend (namely, Scudo).

To solve this, we re-introduce `kUseSeparateSizeClassForBatch` for the 32-bit
Primary allowing for `TransferBatch` to end up in their own memory region.
Currently only Scudo would use this new feature, the default behavior remains
unchanged. The separate `kBatchClassID` was used for a brief period of time
previously but removed when the 64-bit ended up using the "free array".

Reviewers: alekseyshl, kcc, eugenis

Reviewed By: alekseyshl

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D37082

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@311891 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/sanitizer_common/tests/sanitizer_allocator_test.cc b/lib/sanitizer_common/tests/sanitizer_allocator_test.cc
index 0def8ee0f..9ec967bee 100644
--- a/lib/sanitizer_common/tests/sanitizer_allocator_test.cc
+++ b/lib/sanitizer_common/tests/sanitizer_allocator_test.cc
@@ -240,6 +240,23 @@ TEST(SanitizerCommon, SizeClassAllocator32Compact) {
   TestSizeClassAllocator<Allocator32Compact>();
 }
 
+struct AP32SeparateBatches {
+  static const uptr kSpaceBeg = 0;
+  static const u64 kSpaceSize = kAddressSpaceSize;
+  static const uptr kMetadataSize = 16;
+  typedef DefaultSizeClassMap SizeClassMap;
+  static const uptr kRegionSizeLog = ::kRegionSizeLog;
+  typedef FlatByteMap<kFlatByteMapSize> ByteMap;
+  typedef NoOpMapUnmapCallback MapUnmapCallback;
+  static const uptr kFlags =
+      SizeClassAllocator32FlagMasks::kUseSeparateSizeClassForBatch;
+};
+typedef SizeClassAllocator32<AP32SeparateBatches> Allocator32SeparateBatches;
+
+TEST(SanitizerCommon, SizeClassAllocator32SeparateBatches) {
+  TestSizeClassAllocator<Allocator32SeparateBatches>();
+}
+
 template <class Allocator>
 void SizeClassAllocatorMetadataStress() {
   Allocator *a = new Allocator;