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