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
|
/*
* fuzzing driver
*
* Copyright Red Hat Inc., 2019
*
* Authors:
* Alexander Bulekov <alxndr@bu.edu>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include <wordexp.h>
#include "sysemu/qtest.h"
#include "sysemu/runstate.h"
#include "sysemu/sysemu.h"
#include "qemu/main-loop.h"
#include "qemu/rcu.h"
#include "tests/qtest/libqos/libqtest.h"
#include "tests/qtest/libqos/qgraph.h"
#include "fuzz.h"
#define MAX_EVENT_LOOPS 10
typedef struct FuzzTargetState {
FuzzTarget *target;
QSLIST_ENTRY(FuzzTargetState) target_list;
} FuzzTargetState;
typedef QSLIST_HEAD(, FuzzTargetState) FuzzTargetList;
static const char *fuzz_arch = TARGET_NAME;
static FuzzTargetList *fuzz_target_list;
static FuzzTarget *fuzz_target;
static QTestState *fuzz_qts;
void flush_events(QTestState *s)
{
int i = MAX_EVENT_LOOPS;
while (g_main_context_pending(NULL) && i-- > 0) {
main_loop_wait(false);
}
}
static QTestState *qtest_setup(void)
{
qtest_server_set_send_handler(&qtest_client_inproc_recv, &fuzz_qts);
return qtest_inproc_init(&fuzz_qts, false, fuzz_arch,
&qtest_server_inproc_recv);
}
void fuzz_add_target(const FuzzTarget *target)
{
FuzzTargetState *tmp;
FuzzTargetState *target_state;
if (!fuzz_target_list) {
fuzz_target_list = g_new0(FuzzTargetList, 1);
}
QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
if (g_strcmp0(tmp->target->name, target->name) == 0) {
fprintf(stderr, "Error: Fuzz target name %s already in use\n",
target->name);
abort();
}
}
target_state = g_new0(FuzzTargetState, 1);
target_state->target = g_new0(FuzzTarget, 1);
*(target_state->target) = *target;
QSLIST_INSERT_HEAD(fuzz_target_list, target_state, target_list);
}
static void usage(char *path)
{
printf("Usage: %s --fuzz-target=FUZZ_TARGET [LIBFUZZER ARGUMENTS]\n", path);
printf("where FUZZ_TARGET is one of:\n");
FuzzTargetState *tmp;
if (!fuzz_target_list) {
fprintf(stderr, "Fuzz target list not initialized\n");
abort();
}
QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
printf(" * %s : %s\n", tmp->target->name,
tmp->target->description);
}
printf("Alternatively, add -target-FUZZ_TARGET to the executable name\n\n"
"Set the environment variable FUZZ_SERIALIZE_QTEST=1 to serialize\n"
"QTest commands into an ASCII protocol. Useful for building crash\n"
"reproducers, but slows down execution.\n\n"
"Set the environment variable QTEST_LOG=1 to log all qtest commands"
"\n");
exit(0);
}
static FuzzTarget *fuzz_get_target(char* name)
{
FuzzTargetState *tmp;
if (!fuzz_target_list) {
fprintf(stderr, "Fuzz target list not initialized\n");
abort();
}
QSLIST_FOREACH(tmp, fuzz_target_list, target_list) {
if (strcmp(tmp->target->name, name) == 0) {
return tmp->target;
}
}
return NULL;
}
/* Executed for each fuzzing-input */
int LLVMFuzzerTestOneInput(const unsigned char *Data, size_t Size)
{
/*
* Do the pre-fuzz-initialization before the first fuzzing iteration,
* instead of before the actual fuzz loop. This is needed since libfuzzer
* may fork off additional workers, prior to the fuzzing loop, and if
* pre_fuzz() sets up e.g. shared memory, this should be done for the
* individual worker processes
*/
static int pre_fuzz_done;
if (!pre_fuzz_done && fuzz_target->pre_fuzz) {
fuzz_target->pre_fuzz(fuzz_qts);
pre_fuzz_done = true;
}
fuzz_target->fuzz(fuzz_qts, Data, Size);
return 0;
}
/* Executed once, prior to fuzzing */
int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
{
char *target_name;
char *bindir, *datadir;
bool serialize = false;
/* Initialize qgraph and modules */
qos_graph_init();
module_call_init(MODULE_INIT_FUZZ_TARGET);
module_call_init(MODULE_INIT_QOM);
module_call_init(MODULE_INIT_LIBQOS);
target_name = strstr(**argv, "-target-");
if (target_name) { /* The binary name specifies the target */
target_name += strlen("-target-");
/*
* With oss-fuzz, the executable is kept in the root of a directory (we
* cannot assume the path). All data (including bios binaries) must be
* in the same dir, or a subdir. Thus, we cannot place the pc-bios so
* that it would be in exec_dir/../pc-bios.
* As a workaround, oss-fuzz allows us to use argv[0] to get the
* location of the executable. Using this we add exec_dir/pc-bios to
* the datadirs.
*/
bindir = g_path_get_dirname(**argv);
datadir = g_build_filename(bindir, "pc-bios", NULL);
g_free(bindir);
if (g_file_test(datadir, G_FILE_TEST_IS_DIR)) {
qemu_add_data_dir(datadir);
}
g_free(datadir);
} else if (*argc > 1) { /* The target is specified as an argument */
target_name = (*argv)[1];
if (!strstr(target_name, "--fuzz-target=")) {
usage(**argv);
}
target_name += strlen("--fuzz-target=");
} else {
usage(**argv);
}
/* Should we always serialize qtest commands? */
if (getenv("FUZZ_SERIALIZE_QTEST")) {
serialize = true;
}
fuzz_qtest_set_serialize(serialize);
/* Identify the fuzz target */
fuzz_target = fuzz_get_target(target_name);
if (!fuzz_target) {
usage(**argv);
}
fuzz_qts = qtest_setup();
if (fuzz_target->pre_vm_init) {
fuzz_target->pre_vm_init();
}
/* Run QEMU's softmmu main with the fuzz-target dependent arguments */
GString *cmd_line = fuzz_target->get_init_cmdline(fuzz_target);
g_string_append_printf(cmd_line, " %s -qtest /dev/null ",
getenv("QTEST_LOG") ? "" : "-qtest-log none");
/* Split the runcmd into an argv and argc */
wordexp_t result;
wordexp(cmd_line->str, &result, 0);
g_string_free(cmd_line, true);
qemu_init(result.we_wordc, result.we_wordv, NULL);
/* re-enable the rcu atfork, which was previously disabled in qemu_init */
rcu_enable_atfork();
return 0;
}
|
