asan_fake_stack.cc revision 86b88b80bdb7ea9a265f8946e7918bcc388abceb
1//===-- asan_fake_stack.cc ------------------------------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file is a part of AddressSanitizer, an address sanity checker. 11// 12// FakeStack is used to detect use-after-return bugs. 13//===----------------------------------------------------------------------===// 14#include "asan_allocator.h" 15#include "asan_poisoning.h" 16#include "asan_thread.h" 17 18namespace __asan { 19 20void FakeStack::PoisonAll(u8 magic) { 21 PoisonShadow(reinterpret_cast<uptr>(this), RequiredSize(stack_size_log()), 22 magic); 23} 24 25FakeFrame *FakeStack::Allocate(uptr stack_size_log, uptr class_id, 26 uptr real_stack) { 27 CHECK_LT(class_id, kNumberOfSizeClasses); 28 uptr &hint_position = hint_position_[class_id]; 29 const int num_iter = NumberOfFrames(stack_size_log, class_id); 30 u8 *flags = GetFlags(stack_size_log, class_id); 31 for (int i = 0; i < num_iter; i++) { 32 uptr pos = ModuloNumberOfFrames(stack_size_log, class_id, hint_position++); 33 if (flags[pos]) continue; 34 // FIXME: this does not have to be thread-safe, just async-signal-safe. 35 if (0 == atomic_exchange((atomic_uint8_t *)&flags[pos], 1, 36 memory_order_relaxed)) { 37 FakeFrame *res = reinterpret_cast<FakeFrame *>( 38 GetFrame(stack_size_log, class_id, pos)); 39 res->real_stack = real_stack; 40 res->class_id = class_id; 41 return res; 42 } 43 } 44 CHECK(0 && "Failed to allocate a fake stack frame"); 45 return 0; 46} 47 48void FakeStack::Deallocate(FakeFrame *ff, uptr stack_size_log, uptr class_id, 49 uptr real_stack) { 50 u8 *base = GetFrame(stack_size_log, class_id, 0); 51 u8 *cur = reinterpret_cast<u8 *>(ff); 52 CHECK_LE(base, cur); 53 CHECK_LT(cur, base + (1UL << stack_size_log)); 54 uptr pos = (cur - base) >> (kMinStackFrameSizeLog + class_id); 55 u8 *flags = GetFlags(stack_size_log, class_id); 56 CHECK_EQ(flags[pos], 1); 57 flags[pos] = 0; 58} 59 60uptr FakeStack::AddrIsInFakeStack(uptr ptr) { 61 uptr stack_size_log = this->stack_size_log(); 62 uptr beg = reinterpret_cast<uptr>(GetFrame(stack_size_log, 0, 0)); 63 uptr end = reinterpret_cast<uptr>(this) + RequiredSize(stack_size_log); 64 if (ptr < beg || ptr >= end) return 0; 65 uptr class_id = (ptr - beg) >> stack_size_log; 66 uptr base = beg + (class_id << stack_size_log); 67 CHECK_LE(base, ptr); 68 CHECK_LT(ptr, base + (1UL << stack_size_log)); 69 uptr pos = (ptr - base) >> (kMinStackFrameSizeLog + class_id); 70 return base + pos * BytesInSizeClass(class_id); 71} 72 73ALWAYS_INLINE uptr OnMalloc(uptr class_id, uptr size, uptr real_stack) { 74 AsanThread *t = GetCurrentThread(); 75 if (!t) return real_stack; 76 FakeStack *fs = t->fake_stack(); 77 FakeFrame *ff = fs->Allocate(fs->stack_size_log(), class_id, real_stack); 78 uptr ptr = reinterpret_cast<uptr>(ff); 79 PoisonShadow(ptr, size, 0); 80 return ptr; 81} 82 83ALWAYS_INLINE void OnFree(uptr ptr, uptr class_id, uptr size, uptr real_stack) { 84 if (ptr == real_stack) 85 return; 86 AsanThread *t = GetCurrentThread(); 87 if (!t) return; 88 FakeStack *fs = t->fake_stack(); 89 FakeFrame *ff = reinterpret_cast<FakeFrame *>(ptr); 90 fs->Deallocate(ff, fs->stack_size_log(), class_id, real_stack); 91 PoisonShadow(ptr, size, kAsanStackAfterReturnMagic); 92} 93 94} // namespace __asan 95 96// ---------------------- Interface ---------------- {{{1 97#define DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(class_id) \ 98 extern "C" SANITIZER_INTERFACE_ATTRIBUTE uptr \ 99 __asan_stack_malloc_##class_id(uptr size, uptr real_stack) { \ 100 return __asan::OnMalloc(class_id, size, real_stack); \ 101 } \ 102 extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __asan_stack_free_##class_id( \ 103 uptr ptr, uptr size, uptr real_stack) { \ 104 __asan::OnFree(ptr, class_id, size, real_stack); \ 105 } 106 107DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(0) 108DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(1) 109DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(2) 110DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(3) 111DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(4) 112DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(5) 113DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(6) 114DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(7) 115DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(8) 116DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(9) 117DEFINE_STACK_MALLOC_FREE_WITH_CLASS_ID(10) 118