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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
content / test / fuzzer / browser_accessibility_fuzzer.cc [blame]
// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/accessibility/platform/browser_accessibility.h"
#include <fuzzer/FuzzedDataProvider.h>
#include <memory>
#include "base/at_exit.h"
#include "base/command_line.h"
#include "content/browser/accessibility/browser_accessibility_state_impl.h"
#include "content/public/common/content_client.h"
#include "content/public/test/browser_task_environment.h"
#include "content/test/test_content_browser_client.h"
#include "content/test/test_content_client.h"
#include "ui/accessibility/platform/browser_accessibility_manager.h"
#include "ui/accessibility/platform/one_shot_accessibility_tree_search.h"
#include "ui/accessibility/platform/test_ax_node_id_delegate.h"
#include "ui/accessibility/platform/test_ax_platform_tree_manager_delegate.h"
struct Env {
Env() {
base::CommandLine::Init(0, nullptr);
// BrowserAccessibilityStateImpl requires a ContentBrowserClient.
content_client_ = std::make_unique<content::TestContentClient>();
content_browser_client_ =
std::make_unique<content::TestContentBrowserClient>();
content::SetContentClient(content_client_.get());
content::SetBrowserClientForTesting(content_browser_client_.get());
}
~Env() {
content::SetBrowserClientForTesting(nullptr);
content::SetContentClient(nullptr);
}
content::BrowserTaskEnvironment task_environment;
std::unique_ptr<content::ContentBrowserClient> content_browser_client_;
std::unique_ptr<content::ContentClient> content_client_;
base::AtExitManager at_exit;
};
namespace content {
// Return an accessibility role to use in a tree to fuzz. Out of the
// dozens of roles, these are the ones that tend to have special meaning
// or otherwise affect the logic in BrowserAccessibility code.
ax::mojom::Role GetInterestingRole(FuzzedDataProvider& fdp) {
switch (fdp.ConsumeIntegralInRange(0, 12)) {
default:
case 0:
return ax::mojom::Role::kNone;
case 1:
return ax::mojom::Role::kStaticText;
case 2:
return ax::mojom::Role::kInlineTextBox;
case 3:
return ax::mojom::Role::kParagraph;
case 4:
return ax::mojom::Role::kLineBreak;
case 5:
return ax::mojom::Role::kGenericContainer;
case 6:
return ax::mojom::Role::kButton;
case 7:
return ax::mojom::Role::kTextField;
case 8:
return ax::mojom::Role::kIframePresentational;
case 9:
return ax::mojom::Role::kIframe;
case 10:
return ax::mojom::Role::kHeading;
case 11:
return ax::mojom::Role::kPopUpButton;
case 12:
return ax::mojom::Role::kLink;
}
}
// Add some states to the node based on the FuzzedDataProvider.
// Currently we're messing with ignored and invisible because that
// affects a lot of the tree walking code.
void AddStates(FuzzedDataProvider& fdp, ui::AXNodeData* node) {
if (fdp.ConsumeBool())
node->AddState(ax::mojom::State::kIgnored);
if (fdp.ConsumeBool())
node->AddState(ax::mojom::State::kInvisible);
}
// Construct an accessibility tree. The shape of the tree is static, but
// some of the properties of the nodes in the tree are determined by
// the fuzz input. Once the tree is constructed, fuzz by calling some
// functions that walk the tree in various ways to ensure they don't crash.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
static Env env;
auto accessibility_state = BrowserAccessibilityStateImpl::Create();
FuzzedDataProvider fdp(data, size);
// The tree structure is always the same, only the data changes.
//
// 1
// / \
// 2 3 4
// / \ / \ / \
// 5 6 7 8 9 10
//
// In addition, there's a child tree that may be linked off one of
// the nodes.
ui::AXTreeID parent_tree_id = ui::AXTreeID::CreateNewAXTreeID();
ui::AXTreeID child_tree_id = ui::AXTreeID::CreateNewAXTreeID();
const int num_nodes = 10;
ui::AXTreeUpdate tree;
tree.root_id = 1;
tree.tree_data.tree_id = parent_tree_id;
tree.has_tree_data = true;
tree.nodes.resize(10);
tree.nodes[0].id = 1;
tree.nodes[0].role = ax::mojom::Role::kRootWebArea;
tree.nodes[0].child_ids = {2, 3, 4};
// The root node cannot be ignored, so we'll only try invisible.
if (fdp.ConsumeBool()) {
tree.nodes[0].AddState(ax::mojom::State::kInvisible);
}
tree.nodes[1].id = 2;
tree.nodes[1].role = GetInterestingRole(fdp);
tree.nodes[1].child_ids = {5, 6};
AddStates(fdp, &tree.nodes[1]);
tree.nodes[2].id = 3;
tree.nodes[2].role = GetInterestingRole(fdp);
tree.nodes[2].child_ids = {7, 8};
AddStates(fdp, &tree.nodes[2]);
tree.nodes[3].id = 4;
tree.nodes[3].role = GetInterestingRole(fdp);
tree.nodes[3].child_ids = {9, 10};
AddStates(fdp, &tree.nodes[3]);
for (int i = 4; i < num_nodes; i++) {
tree.nodes[i].id = i + 1;
tree.nodes[i].role = GetInterestingRole(fdp);
AddStates(fdp, &tree.nodes[i]);
}
for (int i = 0; i < num_nodes; i++)
tree.nodes[i].SetName(fdp.ConsumeRandomLengthString(5));
// Optionally, embed the child tree in the parent tree.
int embedder_node = fdp.ConsumeIntegralInRange(0, num_nodes);
if (embedder_node > 0)
tree.nodes[embedder_node - 1].AddStringAttribute(
ax::mojom::StringAttribute::kChildTreeId, child_tree_id.ToString());
VLOG(1) << tree.ToString();
// The child tree is trivial, just one node. That's still enough to exercise
// a lot of paths.
ui::AXTreeUpdate child_tree;
child_tree.root_id = 1;
child_tree.tree_data.tree_id = child_tree_id;
child_tree.has_tree_data = true;
child_tree.nodes.resize(1);
child_tree.nodes[0].id = 1;
child_tree.nodes[0].role = ax::mojom::Role::kRootWebArea;
VLOG(1) << child_tree.ToString();
ui::TestAXPlatformTreeManagerDelegate delegate;
ui::TestAXNodeIdDelegate node_id_delegate;
std::unique_ptr<ui::BrowserAccessibilityManager> manager(
ui::BrowserAccessibilityManager::Create(tree, node_id_delegate,
&delegate));
std::unique_ptr<ui::BrowserAccessibilityManager> child_manager(
ui::BrowserAccessibilityManager::Create(child_tree, node_id_delegate,
&delegate));
// We want to call a bunch of functions but we don't care what the
// return values are. To ensure the compiler doesn't optimize the calls
// away, push the return values onto a vector and make an assertion about
// it at the end.
std::vector<void*> results;
// Test some tree-walking functions.
ui::BrowserAccessibility* root = manager->GetBrowserAccessibilityRoot();
results.push_back(root->PlatformDeepestFirstChild());
results.push_back(root->PlatformDeepestLastChild());
results.push_back(root->InternalDeepestFirstChild());
results.push_back(root->InternalDeepestLastChild());
// Test OneShotAccessibilityTreeSearch.
ui::OneShotAccessibilityTreeSearch search(
manager->GetBrowserAccessibilityRoot());
search.SetDirection(fdp.ConsumeBool()
? ui::OneShotAccessibilityTreeSearch::FORWARDS
: ui::OneShotAccessibilityTreeSearch::BACKWARDS);
search.SetImmediateDescendantsOnly(fdp.ConsumeBool());
search.SetCanWrapToLastElement(fdp.ConsumeBool());
search.SetOnscreenOnly(fdp.ConsumeBool());
if (fdp.ConsumeBool())
search.AddPredicate(ui::AccessibilityButtonPredicate);
if (fdp.ConsumeBool())
search.SetSearchText(fdp.ConsumeRandomLengthString(5));
size_t matches = search.CountMatches();
for (size_t i = 0; i < matches; i++) {
results.push_back(search.GetMatchAtIndex(i));
}
// This is just to ensure that none of the above code gets optimized away.
CHECK_NE(0U, results.size());
// Add a node, possibly clearing old children.
int node_id = num_nodes + 1;
int parent = fdp.ConsumeIntegralInRange(1, num_nodes);
ui::AXTreeUpdate update;
update.nodes.resize(2);
update.nodes[0].id = parent;
update.nodes[0].child_ids = {node_id};
update.nodes[1].id = node_id;
update.nodes[1].role = GetInterestingRole(fdp);
AddStates(fdp, &update.nodes[1]);
ui::AXUpdatesAndEvents notification;
notification.updates.resize(1);
notification.updates[0] = update;
CHECK(manager->OnAccessibilityEvents(notification));
return 0;
}
} // namespace content