Make sure that not interesting allocas are not instrumented.

Summary:
We failed to unpoison uninteresting allocas on return as unpoisoning is part of
main instrumentation which skips such allocas.

Added check -asan-instrument-allocas for dynamic allocas. If instrumentation of
dynamic allocas is disabled it will not will not be unpoisoned.

PR27453

Reviewers: kcc, eugenis

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21207

llvm-svn: 272341

1 files changed, 13 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index af83eea3273..08f148139a2 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -745,7 +745,8 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
       return;
     // Find alloca instruction that corresponds to llvm.lifetime argument.
     AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
-    if (!AI) return;
+    if (!AI || !ASan.isInterestingAlloca(*AI))
+      return;
     bool DoPoison = (ID == Intrinsic::lifetime_end);
     AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
     AllocaPoisonCallVec.push_back(APC);
@@ -1984,13 +1985,21 @@ void FunctionStackPoisoner::poisonStack() {
   assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
 
   // Insert poison calls for lifetime intrinsics for alloca.
-  bool HavePoisonedAllocas = false;
+  bool HavePoisonedStaticAllocas = false;
   for (const auto &APC : AllocaPoisonCallVec) {
     assert(APC.InsBefore);
     assert(APC.AI);
+    assert(ASan.isInterestingAlloca(*APC.AI));
+    bool IsDynamicAlloca = ASan.isDynamicAlloca(*APC.AI);
+    if (!ClInstrumentAllocas && IsDynamicAlloca)
+      continue;
+
     IRBuilder<> IRB(APC.InsBefore);
     poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
-    HavePoisonedAllocas |= APC.DoPoison;
+    // Dynamic allocas will be unpoisoned unconditionally below in
+    // unpoisonDynamicAllocas.
+    // Flag that we need unpoison static allocas.
+    HavePoisonedStaticAllocas |= (APC.DoPoison && !IsDynamicAlloca);
   }
 
   if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
@@ -2137,7 +2146,7 @@ void FunctionStackPoisoner::poisonStack() {
   poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
 
   auto UnpoisonStack = [&](IRBuilder<> &IRB) {
-    if (HavePoisonedAllocas) {
+    if (HavePoisonedStaticAllocas) {
       // If we poisoned some allocas in llvm.lifetime analysis,
       // unpoison whole stack frame now.
       poisonAlloca(LocalStackBase, LocalStackSize, IRB, false);