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/*
* 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;
const char *bindir;
char *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);
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;
}
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