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#include <iostream>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <dlfcn.h>
#ifdef __ANDROID__
# include "../include/android-ashmem.h"
#endif
#include <sys/ipc.h>
#include <sys/shm.h>
#include "../config.h"
#include <QBDI.h>
/* NeverZero */
#if (defined(__x86_64__) || defined(__i386__)) && defined(AFL_QEMU_NOT_ZERO)
# define INC_AFL_AREA(loc) \
asm volatile( \
"incb (%0, %1, 1)\n" \
"adcb $0, (%0, %1, 1)\n" \
: /* no out */ \
: "r"(afl_area_ptr), "r"(loc) \
: "memory", "eax")
#else
# define INC_AFL_AREA(loc) afl_area_ptr[loc]++
#endif
using namespace QBDI;
typedef int (*target_func)(char *buf, int size);
static const size_t STACK_SIZE = 0x100000; // 1MB
static const QBDI::rword FAKE_RET_ADDR = 0x40000;
target_func p_target_func = NULL;
rword module_base = 0;
rword module_end = 0;
static unsigned char
dummy[MAP_SIZE]; /* costs MAP_SIZE but saves a few instructions */
unsigned char *afl_area_ptr = NULL; /* Exported for afl_gen_trace */
unsigned long afl_prev_loc = 0;
char input_pathname[PATH_MAX];
/* Set up SHM region and initialize other stuff. */
int afl_setup(void) {
char *id_str = getenv(SHM_ENV_VAR);
int shm_id;
if (id_str) {
shm_id = atoi(id_str);
afl_area_ptr = (unsigned char *)shmat(shm_id, NULL, 0);
if (afl_area_ptr == (void *)-1) return 0;
memset(afl_area_ptr, 0, MAP_SIZE);
}
return 1;
}
/* Fork server logic, invoked once we hit _start. */
static void afl_forkserver() {
static unsigned char tmp[4];
pid_t child_pid;
if (write(FORKSRV_FD + 1, tmp, 4) != 4) return;
while (1) {
int status;
u32 was_killed;
// wait for afl-fuzz
if (read(FORKSRV_FD, &was_killed, 4) != 4) exit(2);
child_pid = fork();
if (child_pid < 0) exit(4);
if (!child_pid) {
// child return to execute code
close(FORKSRV_FD);
close(FORKSRV_FD + 1);
return;
}
// write child pid to afl-fuzz
if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) exit(5);
// wait child stop
if (waitpid(child_pid, &status, 0) < 0) exit(6);
// send child stop status to afl-fuzz
if (write(FORKSRV_FD + 1, &status, 4) != 4) exit(7);
}
}
void afl_maybe_log(unsigned long cur_loc) {
if (afl_area_ptr == NULL) { return; }
unsigned long afl_idx = cur_loc ^ afl_prev_loc;
afl_idx &= MAP_SIZE - 1;
INC_AFL_AREA(afl_idx);
afl_prev_loc = cur_loc >> 1;
}
char *read_file(char *path, unsigned long *length) {
unsigned long len;
char * buf;
FILE *fp = fopen(path, "rb");
fseek(fp, 0, SEEK_END);
len = ftell(fp);
buf = (char *)malloc(len);
rewind(fp);
fread(buf, 1, len, fp);
fclose(fp);
*length = len;
return buf;
}
QBDI_NOINLINE int fuzz_func() {
if (afl_setup()) { afl_forkserver(); }
unsigned long len = 0;
char * data = read_file(input_pathname, &len);
// printf("In fuzz_func\n");
p_target_func(data, len);
return 1;
}
static QBDI::VMAction bbcallback(QBDI::VMInstanceRef vm,
const QBDI::VMState *state,
QBDI::GPRState * gprState,
QBDI::FPRState *fprState, void *data) {
// errno = SAVED_ERRNO;
#ifdef __x86_64__
unsigned long pc = gprState->rip;
#elif defined(i386)
unsigned long pc = gprState->eip;
#elif defined(__arm__)
unsigned long pc = gprState->pc;
#endif
// just log the module path
if (pc >= module_base && pc <= module_end) {
unsigned long offset = pc - module_base;
printf("\toffset:%p\n", offset);
afl_maybe_log(offset);
}
return QBDI::VMAction::CONTINUE;
}
int main(int argc, char **argv) {
if (argc < 3) {
puts("usage: ./loader library_path input_file_path");
exit(0);
}
const char *lib_path;
lib_path = argv[1];
strcpy(input_pathname, argv[2]);
void *handle = dlopen(lib_path, RTLD_LAZY);
if (handle == nullptr) {
perror("Cannot load library");
exit(EXIT_FAILURE);
}
const char *lib_name = lib_path;
if (strrchr(lib_name, '/') != nullptr) lib_name = strrchr(lib_name, '/') + 1;
// printf("library name:%s\n", lib_name);
// load library module address for log path
for (MemoryMap &map : getCurrentProcessMaps()) {
// printf("module:%s\n", map.name.c_str());
if ((map.permission & PF_EXEC) &&
strstr(map.name.c_str(), lib_name) != NULL) {
module_base = map.range.start;
module_end = map.range.end;
}
}
if (module_base == 0) {
std::cerr << "Fail to find base address" << std::endl;
return -1;
}
// printf("module base:%p, module end:%p\n", module_base, module_end);
p_target_func = (target_func)dlsym(handle, "target_func");
// p_target_func = (target_func)(module_base + 0x61a);
printf("p_target_func:%p\n", p_target_func);
VM vm;
uint8_t *fakestack = nullptr;
GPRState *state = vm.getGPRState();
allocateVirtualStack(state, STACK_SIZE, &fakestack);
vm.addInstrumentedModuleFromAddr(module_base);
vm.addInstrumentedModuleFromAddr((rword)&main);
vm.addVMEventCB(BASIC_BLOCK_ENTRY, bbcallback, nullptr);
// QBDI::simulateCall(state, FAKE_RET_ADDR);
// vm.run((rword)&fuzz_func, (rword)FAKE_RET_ADDR);
rword ret;
vm.call(&ret, (rword)&fuzz_func, {});
return 0;
}
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