libsanitizer/asan/asan_poisoning.h

   1 //===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // Shadow memory poisoning by ASan RTL and by user application.
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "asan_interceptors.h"
  14 #include "asan_internal.h"
  15 #include "asan_mapping.h"
  16
  17 namespace __asan {
  18
  19 // Poisons the shadow memory for "size" bytes starting from "addr".
  20 void PoisonShadow(uptr addr, uptr size, u8 value);
  21
  22 // Poisons the shadow memory for "redzone_size" bytes starting from
  23 // "addr + size".
  24 void PoisonShadowPartialRightRedzone(uptr addr,
  25                                      uptr size,
  26                                      uptr redzone_size,
  27                                      u8 value);
  28
  29 // Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
  30 // assume that memory addresses are properly aligned. Use in
  31 // performance-critical code with care.
  32 ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
  33                                     u8 value) {
  34   DCHECK(flags()->poison_heap);
  35   uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
  36   uptr shadow_end = MEM_TO_SHADOW(
  37       aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1;
  38   REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
  39 }
  40
  41 ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
  42     uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
  43   DCHECK(flags()->poison_heap);
  44   bool poison_partial = flags()->poison_partial;
  45   u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
  46   for (uptr i = 0; i < redzone_size; i += SHADOW_GRANULARITY, shadow++) {
  47     if (i + SHADOW_GRANULARITY <= size) {
  48       *shadow = 0;  // fully addressable
  49     } else if (i >= size) {
  50       *shadow = (SHADOW_GRANULARITY == 128) ? 0xff : value;  // unaddressable
  51     } else {
  52       // first size-i bytes are addressable
  53       *shadow = poison_partial ? static_cast<u8>(size - i) : 0;
  54     }
  55   }
  56 }
  57
  58 }  // namespace __asan