asan_poisoning.h revision cca8e781e5353cba810a0ec3a814ddde2c4934e7 
1//===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
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// Shadow memory poisoning by ASan RTL and by user application.
13//===----------------------------------------------------------------------===//
14
15#include "asan_interceptors.h"
16#include "asan_internal.h"
17#include "asan_mapping.h"
18
19namespace __asan {
20
21// Poisons the shadow memory for "size" bytes starting from "addr".
22void PoisonShadow(uptr addr, uptr size, u8 value);
23
24// Poisons the shadow memory for "redzone_size" bytes starting from
25// "addr + size".
26void PoisonShadowPartialRightRedzone(uptr addr,
27                                     uptr size,
28                                     uptr redzone_size,
29                                     u8 value);
30
31// Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
32// assume that memory addresses are properly aligned. Use in
33// performance-critical code with care.
34ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
35                                    u8 value) {
36  DCHECK(flags()->poison_heap);
37  uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
38  uptr shadow_end = MEM_TO_SHADOW(
39      aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1;
40  REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
41}
42
43ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
44    uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
45  DCHECK(flags()->poison_heap);
46  bool poison_partial = flags()->poison_partial;
47  u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
48  for (uptr i = 0; i < redzone_size; i += SHADOW_GRANULARITY, shadow++) {
49    if (i + SHADOW_GRANULARITY <= size) {
50      *shadow = 0;  // fully addressable
51    } else if (i >= size) {
52      *shadow = (SHADOW_GRANULARITY == 128) ? 0xff : value;  // unaddressable
53    } else {
54      // first size-i bytes are addressable
55      *shadow = poison_partial ? static_cast<u8>(size - i) : 0;
56    }
57  }
58}
59
60}  // namespace __asan
61