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//===-- 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"
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);
}
}
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