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
|
/*
* Copyright (C) 2003 Apple Computer, Inc.
* Copyright (C) Research In Motion Limited 2010. All rights reserved.
*
* Portions are Copyright (C) 1998 Netscape Communications Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Alternatively, the contents of this file may be used under the terms
* of either the Mozilla Public License Version 1.1, found at
* http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
* License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
* (the "GPL"), in which case the provisions of the MPL or the GPL are
* applicable instead of those above. If you wish to allow use of your
* version of this file only under the terms of one of those two
* licenses (the MPL or the GPL) and not to allow others to use your
* version of this file under the LGPL, indicate your decision by
* deletingthe provisions above and replace them with the notice and
* other provisions required by the MPL or the GPL, as the case may be.
* If you do not delete the provisions above, a recipient may use your
* version of this file under any of the LGPL, the MPL or the GPL.
*/
#include "config.h"
#include "RenderArena.h"
#include <limits>
#include <stdlib.h>
#include <string.h>
#include <wtf/Assertions.h>
#include <wtf/CryptographicallyRandomNumber.h>
#define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y))
#ifdef NDEBUG
static void* MaskPtr(void* p, uintptr_t mask)
{
return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(p) ^ mask);
}
#endif
namespace WebCore {
#ifndef NDEBUG
const int signature = 0xDBA00AEA;
const int signatureDead = 0xDBA00AED;
typedef struct {
RenderArena* arena;
size_t size;
int signature;
} RenderArenaDebugHeader;
static const size_t debugHeaderSize = ARENA_ALIGN(sizeof(RenderArenaDebugHeader));
#endif
RenderArena::RenderArena(unsigned arenaSize)
: m_totalSize(0)
, m_totalAllocated(0)
{
ASSERT(arenaSize > sizeof(Arena) + ARENA_ALIGN_MASK);
// The underlying Arena class allocates some metadata on top of our
// requested size. Factor this in so that we can get perfect power-of-two
// allocation sizes passed to the underlying malloc() call.
arenaSize -= (sizeof(Arena) + ARENA_ALIGN_MASK);
// Initialize the arena pool
INIT_ARENA_POOL(&m_pool, "RenderArena", arenaSize);
// Zero out the recyclers array
memset(m_recyclers, 0, sizeof(m_recyclers));
// Mask freelist pointers to detect corruption and stop freelist spraying.
// We use an arbitray function and rely on ASLR to randomize it.
// The first value in RenderObject (or any class) is a vtable pointer, which
// always overlaps with the next pointer. This change guarantees that the
// masked vtable/next pointer will never point to valid memory. So, we
// should immediately crash on the first invalid vtable access for a stale
// RenderObject pointer.
// See http://download.crowdstrike.com/papers/hes-exploiting-a-coalmine.pdf.
WTF::cryptographicallyRandomValues(&m_mask, sizeof(m_mask));
m_mask |= (static_cast<uintptr_t>(3) << (std::numeric_limits<uintptr_t>::digits - 2)) | 1;
}
RenderArena::~RenderArena()
{
FinishArenaPool(&m_pool);
}
void* RenderArena::allocate(size_t size)
{
ASSERT(size <= gMaxRecycledSize - 32);
m_totalSize += size;
#ifdef ADDRESS_SANITIZER
return ::malloc(size);
#elif !defined(NDEBUG)
// Use standard malloc so that memory debugging tools work.
ASSERT(this);
void* block = ::malloc(debugHeaderSize + size);
RenderArenaDebugHeader* header = static_cast<RenderArenaDebugHeader*>(block);
header->arena = this;
header->size = size;
header->signature = signature;
return static_cast<char*>(block) + debugHeaderSize;
#else
// Ensure we have correct alignment for pointers. Important for Tru64
size = ROUNDUP(size, sizeof(void*));
const size_t index = size >> kRecyclerShift;
void* result = m_recyclers[index];
if (result) {
// Need to move to the next object
void* next = MaskPtr(*((void**)result), m_mask);
m_recyclers[index] = next;
}
if (!result) {
// Allocate a new chunk from the arena
unsigned bytesAllocated = 0;
ARENA_ALLOCATE(result, &m_pool, size, &bytesAllocated);
m_totalAllocated += bytesAllocated;
}
return result;
#endif
}
void RenderArena::free(size_t size, void* ptr)
{
ASSERT(size <= gMaxRecycledSize - 32);
m_totalSize -= size;
#ifdef ADDRESS_SANITIZER
::free(ptr);
#elif !defined(NDEBUG)
// Use standard free so that memory debugging tools work.
void* block = static_cast<char*>(ptr) - debugHeaderSize;
RenderArenaDebugHeader* header = static_cast<RenderArenaDebugHeader*>(block);
ASSERT(header->signature == signature);
ASSERT_UNUSED(size, header->size == size);
ASSERT(header->arena == this);
header->signature = signatureDead;
::free(block);
#else
// Ensure we have correct alignment for pointers. Important for Tru64
size = ROUNDUP(size, sizeof(void*));
const size_t index = size >> kRecyclerShift;
void* currentTop = m_recyclers[index];
m_recyclers[index] = ptr;
*((void**)ptr) = MaskPtr(currentTop, m_mask);
#endif
}
} // namespace WebCore
|
