1 files changed, 180 insertions, 0 deletions
diff --git a/libsanitizer/asan/asan_fake_stack.cc b/libsanitizer/asan/asan_fake_stack.cc
new file mode 100644
index 00000000000..e8d1e78488b
--- /dev/null
+++ b/libsanitizer/asan/asan_fake_stack.cc
@@ -0,0 +1,180 @@
+//===-- asan_fake_stack.cc ------------------------------------------------===//
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// FakeStack is used to detect use-after-return bugs.
+//===----------------------------------------------------------------------===//
+#include "asan_allocator.h"
+#include "asan_thread.h"
+#include "asan_thread_registry.h"
+#include "sanitizer/asan_interface.h"
+
+namespace __asan {
+
+FakeStack::FakeStack() {
+  CHECK(REAL(memset) != 0);
+  REAL(memset)(this, 0, sizeof(*this));
+}
+
+bool FakeStack::AddrIsInSizeClass(uptr addr, uptr size_class) {
+  uptr mem = allocated_size_classes_[size_class];
+  uptr size = ClassMmapSize(size_class);
+  bool res = mem && addr >= mem && addr < mem + size;
+  return res;
+}
+
+uptr FakeStack::AddrIsInFakeStack(uptr addr) {
+  for (uptr i = 0; i < kNumberOfSizeClasses; i++) {
+    if (AddrIsInSizeClass(addr, i)) return allocated_size_classes_[i];
+  }
+  return 0;
+}
+
+// We may want to compute this during compilation.
+inline uptr FakeStack::ComputeSizeClass(uptr alloc_size) {
+  uptr rounded_size = RoundUpToPowerOfTwo(alloc_size);
+  uptr log = Log2(rounded_size);
+  CHECK(alloc_size <= (1UL << log));
+  if (!(alloc_size > (1UL << (log-1)))) {
+    Printf("alloc_size %zu log %zu\n", alloc_size, log);
+  }
+  CHECK(alloc_size > (1UL << (log-1)));
+  uptr res = log < kMinStackFrameSizeLog ? 0 : log - kMinStackFrameSizeLog;
+  CHECK(res < kNumberOfSizeClasses);
+  CHECK(ClassSize(res) >= rounded_size);
+  return res;
+}
+
+void FakeFrameFifo::FifoPush(FakeFrame *node) {
+  CHECK(node);
+  node->next = 0;
+  if (first_ == 0 && last_ == 0) {
+    first_ = last_ = node;
+  } else {
+    CHECK(first_);
+    CHECK(last_);
+    last_->next = node;
+    last_ = node;
+  }
+}
+
+FakeFrame *FakeFrameFifo::FifoPop() {
+  CHECK(first_ && last_ && "Exhausted fake stack");
+  FakeFrame *res = 0;
+  if (first_ == last_) {
+    res = first_;
+    first_ = last_ = 0;
+  } else {
+    res = first_;
+    first_ = first_->next;
+  }
+  return res;
+}
+
+void FakeStack::Init(uptr stack_size) {
+  stack_size_ = stack_size;
+  alive_ = true;
+}
+
+void FakeStack::Cleanup() {
+  alive_ = false;
+  for (uptr i = 0; i < kNumberOfSizeClasses; i++) {
+    uptr mem = allocated_size_classes_[i];
+    if (mem) {
+      PoisonShadow(mem, ClassMmapSize(i), 0);
+      allocated_size_classes_[i] = 0;
+      UnmapOrDie((void*)mem, ClassMmapSize(i));
+    }
+  }
+}
+
+uptr FakeStack::ClassMmapSize(uptr size_class) {
+  return RoundUpToPowerOfTwo(stack_size_);
+}
+
+void FakeStack::AllocateOneSizeClass(uptr size_class) {
+  CHECK(ClassMmapSize(size_class) >= GetPageSizeCached());
+  uptr new_mem = (uptr)MmapOrDie(
+      ClassMmapSize(size_class), __FUNCTION__);
+  // Printf("T%d new_mem[%zu]: %p-%p mmap %zu\n",
+  //       asanThreadRegistry().GetCurrent()->tid(),
+  //       size_class, new_mem, new_mem + ClassMmapSize(size_class),
+  //       ClassMmapSize(size_class));
+  uptr i;
+  for (i = 0; i < ClassMmapSize(size_class);
+       i += ClassSize(size_class)) {
+    size_classes_[size_class].FifoPush((FakeFrame*)(new_mem + i));
+  }
+  CHECK(i == ClassMmapSize(size_class));
+  allocated_size_classes_[size_class] = new_mem;
+}
+
+uptr FakeStack::AllocateStack(uptr size, uptr real_stack) {
+  if (!alive_) return real_stack;
+  CHECK(size <= kMaxStackMallocSize && size > 1);
+  uptr size_class = ComputeSizeClass(size);
+  if (!allocated_size_classes_[size_class]) {
+    AllocateOneSizeClass(size_class);
+  }
+  FakeFrame *fake_frame = size_classes_[size_class].FifoPop();
+  CHECK(fake_frame);
+  fake_frame->size_minus_one = size - 1;
+  fake_frame->real_stack = real_stack;
+  while (FakeFrame *top = call_stack_.top()) {
+    if (top->real_stack > real_stack) break;
+    call_stack_.LifoPop();
+    DeallocateFrame(top);
+  }
+  call_stack_.LifoPush(fake_frame);
+  uptr ptr = (uptr)fake_frame;
+  PoisonShadow(ptr, size, 0);
+  return ptr;
+}
+
+void FakeStack::DeallocateFrame(FakeFrame *fake_frame) {
+  CHECK(alive_);
+  uptr size = fake_frame->size_minus_one + 1;
+  uptr size_class = ComputeSizeClass(size);
+  CHECK(allocated_size_classes_[size_class]);
+  uptr ptr = (uptr)fake_frame;
+  CHECK(AddrIsInSizeClass(ptr, size_class));
+  CHECK(AddrIsInSizeClass(ptr + size - 1, size_class));
+  size_classes_[size_class].FifoPush(fake_frame);
+}
+
+void FakeStack::OnFree(uptr ptr, uptr size, uptr real_stack) {
+  FakeFrame *fake_frame = (FakeFrame*)ptr;
+  CHECK(fake_frame->magic = kRetiredStackFrameMagic);
+  CHECK(fake_frame->descr != 0);
+  CHECK(fake_frame->size_minus_one == size - 1);
+  PoisonShadow(ptr, size, kAsanStackAfterReturnMagic);
+}
+
+}  // namespace __asan
+
+// ---------------------- Interface ---------------- {{{1
+using namespace __asan;  // NOLINT
+
+uptr __asan_stack_malloc(uptr size, uptr real_stack) {
+  if (!flags()->use_fake_stack) return real_stack;
+  AsanThread *t = asanThreadRegistry().GetCurrent();
+  if (!t) {
+    // TSD is gone, use the real stack.
+    return real_stack;
+  }
+  uptr ptr = t->fake_stack().AllocateStack(size, real_stack);
+  // Printf("__asan_stack_malloc %p %zu %p\n", ptr, size, real_stack);
+  return ptr;
+}
+
+void __asan_stack_free(uptr ptr, uptr size, uptr real_stack) {
+  if (!flags()->use_fake_stack) return;
+  if (ptr != real_stack) {
+    FakeStack::OnFree(ptr, size, real_stack);
+  }
+}