ebevhan created this revision.
ebevhan added a reviewer: aaron.ballman.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
CGLoopInfo was keeping pointers to parent loop LoopInfos,
but when the loop info vector grew, it reallocated the
storage and invalidated all of the parent pointers, causing
use-after-free.
Manage the lifetimes of the LoopInfos separately so that
the pointers aren't stale.
Repository:
rC Clang
https://reviews.llvm.org/D66206
Files:
lib/CodeGen/CGLoopInfo.cpp
lib/CodeGen/CGLoopInfo.h
test/CodeGen/loop-info-asan.c
Index: test/CodeGen/loop-info-asan.c
===================================================================
--- /dev/null
+++ test/CodeGen/loop-info-asan.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64 -emit-llvm %s -o /dev/null
+
+// This test should not exhibit use-after-free in LoopInfo.
+
+int a() {
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ ;
+}
Index: lib/CodeGen/CGLoopInfo.h
===================================================================
--- lib/CodeGen/CGLoopInfo.h
+++ lib/CodeGen/CGLoopInfo.h
@@ -275,11 +275,11 @@
bool hasInfo() const { return !Active.empty(); }
/// Return the LoopInfo for the current loop. HasInfo should be called
/// first to ensure LoopInfo is present.
- const LoopInfo &getInfo() const { return Active.back(); }
+ const LoopInfo &getInfo() const { return *Active.back(); }
/// The set of attributes that will be applied to the next pushed loop.
LoopAttributes StagedAttrs;
/// Stack of active loops.
- llvm::SmallVector<LoopInfo, 4> Active;
+ llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
};
} // end namespace CodeGen
Index: lib/CodeGen/CGLoopInfo.cpp
===================================================================
--- lib/CodeGen/CGLoopInfo.cpp
+++ lib/CodeGen/CGLoopInfo.cpp
@@ -554,8 +554,9 @@
void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
const llvm::DebugLoc &EndLoc) {
- Active.push_back(LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
- Active.empty() ? nullptr : &Active.back()));
+ Active.emplace_back(
+ new LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
+ Active.empty() ? nullptr : Active.back().get()));
// Clear the attributes so nested loops do not inherit them.
StagedAttrs.clear();
}
@@ -747,16 +748,16 @@
void LoopInfoStack::pop() {
assert(!Active.empty() && "No active loops to pop");
- Active.back().finish();
+ Active.back()->finish();
Active.pop_back();
}
void LoopInfoStack::InsertHelper(Instruction *I) const {
if (I->mayReadOrWriteMemory()) {
SmallVector<Metadata *, 4> AccessGroups;
- for (const LoopInfo &AL : Active) {
+ for (const auto &AL : Active) {
// Here we assume that every loop that has an access group is parallel.
- if (MDNode *Group = AL.getAccessGroup())
+ if (MDNode *Group = AL->getAccessGroup())
AccessGroups.push_back(Group);
}
MDNode *UnionMD = nullptr;
Index: test/CodeGen/loop-info-asan.c
===================================================================
--- /dev/null
+++ test/CodeGen/loop-info-asan.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64 -emit-llvm %s -o /dev/null
+
+// This test should not exhibit use-after-free in LoopInfo.
+
+int a() {
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ for (;;)
+ ;
+}
Index: lib/CodeGen/CGLoopInfo.h
===================================================================
--- lib/CodeGen/CGLoopInfo.h
+++ lib/CodeGen/CGLoopInfo.h
@@ -275,11 +275,11 @@
bool hasInfo() const { return !Active.empty(); }
/// Return the LoopInfo for the current loop. HasInfo should be called
/// first to ensure LoopInfo is present.
- const LoopInfo &getInfo() const { return Active.back(); }
+ const LoopInfo &getInfo() const { return *Active.back(); }
/// The set of attributes that will be applied to the next pushed loop.
LoopAttributes StagedAttrs;
/// Stack of active loops.
- llvm::SmallVector<LoopInfo, 4> Active;
+ llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
};
} // end namespace CodeGen
Index: lib/CodeGen/CGLoopInfo.cpp
===================================================================
--- lib/CodeGen/CGLoopInfo.cpp
+++ lib/CodeGen/CGLoopInfo.cpp
@@ -554,8 +554,9 @@
void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
const llvm::DebugLoc &EndLoc) {
- Active.push_back(LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
- Active.empty() ? nullptr : &Active.back()));
+ Active.emplace_back(
+ new LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
+ Active.empty() ? nullptr : Active.back().get()));
// Clear the attributes so nested loops do not inherit them.
StagedAttrs.clear();
}
@@ -747,16 +748,16 @@
void LoopInfoStack::pop() {
assert(!Active.empty() && "No active loops to pop");
- Active.back().finish();
+ Active.back()->finish();
Active.pop_back();
}
void LoopInfoStack::InsertHelper(Instruction *I) const {
if (I->mayReadOrWriteMemory()) {
SmallVector<Metadata *, 4> AccessGroups;
- for (const LoopInfo &AL : Active) {
+ for (const auto &AL : Active) {
// Here we assume that every loop that has an access group is parallel.
- if (MDNode *Group = AL.getAccessGroup())
+ if (MDNode *Group = AL->getAccessGroup())
AccessGroups.push_back(Group);
}
MDNode *UnionMD = nullptr;
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