[asan] fix a bug (issue 19) where dlclose and the following mmap caused a false positive. compiler part.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146688 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 1 deletions

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 4d6e74b833..e4f197853e 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -55,8 +55,11 @@ static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
 
 static const char *kAsanModuleCtorName = "asan.module_ctor";
+static const char *kAsanModuleDtorName = "asan.module_dtor";
+static const int   kAsanCtorAndCtorPriority = 1;
 static const char *kAsanReportErrorTemplate = "__asan_report_";
 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
+static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
 static const char *kAsanInitName = "__asan_init";
 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
@@ -559,6 +562,22 @@ bool AddressSanitizer::insertGlobalRedzones(Module &M) {
                   IRB.CreatePointerCast(AllGlobals, IntptrTy),
                   ConstantInt::get(IntptrTy, n));
 
+  // We also need to unregister globals at the end, e.g. when a shared library
+  // gets closed.
+  Function *AsanDtorFunction = Function::Create(
+      FunctionType::get(Type::getVoidTy(*C), false),
+      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
+  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
+  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
+  Function *AsanUnregisterGlobals = cast<Function>(M.getOrInsertFunction(
+      kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
+  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
+
+  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
+                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
+                       ConstantInt::get(IntptrTy, n));
+  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
+
   DEBUG(dbgs() << M);
   return true;
 }
@@ -632,7 +651,7 @@ bool AddressSanitizer::runOnModule(Module &M) {
     Res |= handleFunction(M, *F);
   }
 
-  appendToGlobalCtors(M, AsanCtorFunction, 1 /*high priority*/);
+  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
 
   return Res;
 }