aboutsummaryrefslogtreecommitdiff
path: root/lib/msan/msan_poisoning.cc
blob: 92134f6a15b81dc99aa6e421ad58025b1e288674 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
//===-- msan_poisoning.cc ---------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of MemorySanitizer.
//
//===----------------------------------------------------------------------===//

#include "msan_poisoning.h"

#include "interception/interception.h"
#include "msan_origin.h"
#include "sanitizer_common/sanitizer_common.h"

DECLARE_REAL(void *, memset, void *dest, int c, uptr n)
DECLARE_REAL(void *, memcpy, void *dest, const void *src, uptr n)
DECLARE_REAL(void *, memmove, void *dest, const void *src, uptr n)

namespace __msan {

u32 GetOriginIfPoisoned(uptr addr, uptr size) {
  unsigned char *s = (unsigned char *)MEM_TO_SHADOW(addr);
  for (uptr i = 0; i < size; ++i)
    if (s[i]) return *(u32 *)SHADOW_TO_ORIGIN(((uptr)s + i) & ~3UL);
  return 0;
}

void SetOriginIfPoisoned(uptr addr, uptr src_shadow, uptr size,
                         u32 src_origin) {
  uptr dst_s = MEM_TO_SHADOW(addr);
  uptr src_s = src_shadow;
  uptr src_s_end = src_s + size;

  for (; src_s < src_s_end; ++dst_s, ++src_s)
    if (*(u8 *)src_s) *(u32 *)SHADOW_TO_ORIGIN(dst_s & ~3UL) = src_origin;
}

void CopyOrigin(const void *dst, const void *src, uptr size,
                StackTrace *stack) {
  if (!MEM_IS_APP(dst) || !MEM_IS_APP(src)) return;

  uptr d = (uptr)dst;
  uptr beg = d & ~3UL;
  // Copy left unaligned origin if that memory is poisoned.
  if (beg < d) {
    u32 o = GetOriginIfPoisoned((uptr)src, d - beg);
    if (o) {
      if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack);
      *(u32 *)MEM_TO_ORIGIN(beg) = o;
    }
    beg += 4;
  }

  uptr end = (d + size) & ~3UL;
  // If both ends fall into the same 4-byte slot, we are done.
  if (end < beg) return;

  // Copy right unaligned origin if that memory is poisoned.
  if (end < d + size) {
    u32 o = GetOriginIfPoisoned((uptr)src + (end - d), (d + size) - end);
    if (o) {
      if (__msan_get_track_origins() > 1) o = ChainOrigin(o, stack);
      *(u32 *)MEM_TO_ORIGIN(end) = o;
    }
  }

  if (beg < end) {
    // Align src up.
    uptr s = ((uptr)src + 3) & ~3UL;
    // FIXME: factor out to msan_copy_origin_aligned
    if (__msan_get_track_origins() > 1) {
      u32 *src = (u32 *)MEM_TO_ORIGIN(s);
      u32 *src_s = (u32 *)MEM_TO_SHADOW(s);
      u32 *src_end = (u32 *)MEM_TO_ORIGIN(s + (end - beg));
      u32 *dst = (u32 *)MEM_TO_ORIGIN(beg);
      u32 src_o = 0;
      u32 dst_o = 0;
      for (; src < src_end; ++src, ++src_s, ++dst) {
        if (!*src_s) continue;
        if (*src != src_o) {
          src_o = *src;
          dst_o = ChainOrigin(src_o, stack);
        }
        *dst = dst_o;
      }
    } else {
      REAL(memcpy)((void *)MEM_TO_ORIGIN(beg), (void *)MEM_TO_ORIGIN(s),
                   end - beg);
    }
  }
}

void MoveShadowAndOrigin(const void *dst, const void *src, uptr size,
                         StackTrace *stack) {
  if (!MEM_IS_APP(dst)) return;
  if (!MEM_IS_APP(src)) return;
  if (src == dst) return;
  REAL(memmove)((void *)MEM_TO_SHADOW((uptr)dst),
                (void *)MEM_TO_SHADOW((uptr)src), size);
  if (__msan_get_track_origins()) CopyOrigin(dst, src, size, stack);
}

void CopyShadowAndOrigin(const void *dst, const void *src, uptr size,
                         StackTrace *stack) {
  if (!MEM_IS_APP(dst)) return;
  if (!MEM_IS_APP(src)) return;
  REAL(memcpy)((void *)MEM_TO_SHADOW((uptr)dst),
               (void *)MEM_TO_SHADOW((uptr)src), size);
  if (__msan_get_track_origins()) CopyOrigin(dst, src, size, stack);
}

void CopyMemory(void *dst, const void *src, uptr size, StackTrace *stack) {
  REAL(memcpy)(dst, src, size);
  CopyShadowAndOrigin(dst, src, size, stack);
}

void SetShadow(const void *ptr, uptr size, u8 value) {
  uptr PageSize = GetPageSizeCached();
  uptr shadow_beg = MEM_TO_SHADOW(ptr);
  uptr shadow_end = shadow_beg + size;
  if (value ||
      shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
    REAL(memset)((void *)shadow_beg, value, shadow_end - shadow_beg);
  } else {
    uptr page_beg = RoundUpTo(shadow_beg, PageSize);
    uptr page_end = RoundDownTo(shadow_end, PageSize);

    if (page_beg >= page_end) {
      REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
    } else {
      if (page_beg != shadow_beg) {
        REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
      }
      if (page_end != shadow_end) {
        REAL(memset)((void *)page_end, 0, shadow_end - page_end);
      }
      MmapFixedNoReserve(page_beg, page_end - page_beg);
    }
  }
}

void SetOrigin(const void *dst, uptr size, u32 origin) {
  // Origin mapping is 4 bytes per 4 bytes of application memory.
  // Here we extend the range such that its left and right bounds are both
  // 4 byte aligned.
  uptr x = MEM_TO_ORIGIN((uptr)dst);
  uptr beg = x & ~3UL;               // align down.
  uptr end = (x + size + 3) & ~3UL;  // align up.
  u64 origin64 = ((u64)origin << 32) | origin;
  // This is like memset, but the value is 32-bit. We unroll by 2 to write
  // 64 bits at once. May want to unroll further to get 128-bit stores.
  if (beg & 7ULL) {
    *(u32 *)beg = origin;
    beg += 4;
  }
  for (uptr addr = beg; addr < (end & ~7UL); addr += 8) *(u64 *)addr = origin64;
  if (end & 7ULL) *(u32 *)(end - 4) = origin;
}

void PoisonMemory(const void *dst, uptr size, StackTrace *stack) {
  SetShadow(dst, size, (u8)-1);

  if (__msan_get_track_origins()) {
    Origin o = Origin::CreateHeapOrigin(stack);
    SetOrigin(dst, size, o.raw_id());
  }
}

}  // namespace __msan