From 7bcfc9950bac0f411f9671e8d6ce483bd219727e Mon Sep 17 00:00:00 2001
From: Kostya Serebryany <kcc@google.com>
Date: Thu, 15 Dec 2011 21:59:03 +0000
Subject: [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
---
 lib/Transforms/Instrumentation/AddressSanitizer.cpp | 21 ++++++++++++++++++++-
 lib/Transforms/Utils/ModuleUtils.cpp                | 16 ++++++++++++----
 2 files changed, 32 insertions(+), 5 deletions(-)

(limited to 'lib/Transforms')

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 4d6e74b..e4f1978 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;
 }
diff --git a/lib/Transforms/Utils/ModuleUtils.cpp b/lib/Transforms/Utils/ModuleUtils.cpp
index 5e294a3..8491c55 100644
--- a/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/lib/Transforms/Utils/ModuleUtils.cpp
@@ -19,7 +19,8 @@
 
 using namespace llvm;
 
-void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
+static void appendToGlobalArray(const char *Array, 
+                                Module &M, Function *F, int Priority) {
   IRBuilder<> IRB(M.getContext());
   FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
   StructType *Ty = StructType::get(
@@ -31,7 +32,7 @@ void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
   // Get the current set of static global constructors and add the new ctor
   // to the list.
   SmallVector<Constant *, 16> CurrentCtors;
-  if (GlobalVariable * GVCtor = M.getNamedGlobal("llvm.global_ctors")) {
+  if (GlobalVariable * GVCtor = M.getNamedGlobal(Array)) {
     if (Constant *Init = GVCtor->getInitializer()) {
       unsigned n = Init->getNumOperands();
       CurrentCtors.reserve(n + 1);
@@ -51,6 +52,13 @@ void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
   // Create the new global variable and replace all uses of
   // the old global variable with the new one.
   (void)new GlobalVariable(M, NewInit->getType(), false,
-                           GlobalValue::AppendingLinkage, NewInit,
-                           "llvm.global_ctors");
+                           GlobalValue::AppendingLinkage, NewInit, Array);
+}
+
+void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority) {
+  appendToGlobalArray("llvm.global_ctors", M, F, Priority);
+}
+
+void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority) {
+  appendToGlobalArray("llvm.global_dtors", M, F, Priority);
 }
-- 
cgit v1.1