Add a test case for the custom mutator

- Update the Makefile in examples/custom_mutators
- Add a test program for testing the custom mutator
- Update test.sh for testing the custom mutator
- [TODO] Update the result checking criterias of the custom mutator in
test.sh

examples/custom_mutators/Makefile

@@ -1,2 +1,7 @@
-all:
+all: libexamplemutator.so
+
+libexamplemutator.so:
 	$(CC) $(CFLAGS) -fPIC -shared -g -I ../../include example.c -o libexamplemutator.so
+
+clean:
+	rm -rf libexamplemutator.so

test/test-custom-mutator.c

@@ -0,0 +1,20 @@
+/**
+ * Reference: https://github.com/bruce30262/libprotobuf-mutator_fuzzing_learning/blob/master/4_libprotobuf_aflpp_custom_mutator/vuln.c
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[])
+{
+    char str[100]={ };
+    read(0, str, 100);
+    int *ptr = NULL;
+    if( str[0] == 'P') {
+        *ptr = 123;
+    }
+    return 0;
+}

test/test.sh

@@ -60,8 +60,8 @@ unset AFL_QEMU_PERSISTENT_GPR
 unset AFL_QEMU_PERSISTENT_RET
 unset AFL_QEMU_PERSISTENT_HOOK
 unset AFL_QEMU_PERSISTENT_CNT
-unset AFL_POST_LIBRARY
-unset AFL_CUSTOM_MUTATOR_LIBRARY
+
+export unset AFL_CUSTOM_MUTATOR_LIBRARY=unset AFL_POST_LIBRARY
 unset AFL_PYTHON_MODULE
 unset AFL_PRELOAD
 unset LD_PRELOAD
@@ -893,6 +893,80 @@ test -d ../unicorn_mode/unicornafl && {
   INCOMPLETE=1
 }
 
+$ECHO "$BLUE[*] Testing: custom mutator"
+unset AFL_CC  # Line 474 sets AFL_CC to "gcc". We reset it to use the default compiler
+CUSTOM_MUTATOR_PATH=../examples/custom_mutators
+test -e test-custom-mutator.c -a -e ${CUSTOM_MUTATOR_PATH}/example.c -a -e ${CUSTOM_MUTATOR_PATH}/example.c && {
+  # Compile the vulnerable program
+  ../afl-clang-fast -o test-custom-mutator test-custom-mutator.c
+  # Compile the custom mutator
+  make -C ../examples/custom_mutators libexamplemutator.so
+  test -e test-custom-mutator -a -e ${CUSTOM_MUTATOR_PATH}/libexamplemutator.so && {
+    # Create input directory
+    mkdir -p in
+    echo 00000 > in/in
+
+    # Run afl-fuzz w/ the C mutator
+    $ECHO "$GREY[*] running afl-fuzz for the C mutator, this will take approx 10 seconds"
+    {
+      export AFL_CUSTOM_MUTATOR_LIBRARY=${CUSTOM_MUTATOR_PATH}/libexamplemutator.so
+      ../afl-fuzz -V10 -m ${MEM_LIMIT} -i in -o out -- ./test-custom-mutator
+      unset AFL_CUSTOM_MUTATOR_LIBRARY
+    } >>errors 2>&1
+
+    # Check results
+    test -n "$( ls out/queue/id:000001* 2>/dev/null )" && {  # TODO: update here
+      $ECHO "$GREEN[+] afl-fuzz is working correctly with the C mutator"
+    } || {
+      echo CUT------------------------------------------------------------------CUT
+      cat errors
+      echo CUT------------------------------------------------------------------CUT
+      $ECHO "$RED[!] afl-fuzz is not working correctly with the C mutator"
+      CODE=1
+    }
+
+    # Clean
+    rm -rf out errors
+
+    # Run afl-fuzz w/ the Python mutator
+    $ECHO "$GREY[*] running afl-fuzz for the Python mutator, this will take approx 10 seconds"
+    {
+      export PYTHONPATH=${CUSTOM_MUTATOR_PATH}
+      export AFL_PYTHON_MODULE=example
+      ../afl-fuzz -V10 -m ${MEM_LIMIT} -i in -o out -- ./test-custom-mutator
+      unset PYTHONPATH
+      unset AFL_PYTHON_MODULE
+    } >>errors 2>&1
+
+    # Check results
+    test -n "$( ls out/queue/id:000001* 2>/dev/null )" && {  # TODO: update here
+      $ECHO "$GREEN[+] afl-fuzz is working correctly with the Python mutator"
+    } || {
+      echo CUT------------------------------------------------------------------CUT
+      cat errors
+      echo CUT------------------------------------------------------------------CUT
+      $ECHO "$RED[!] afl-fuzz is not working correctly with the Python mutator"
+      CODE=1
+    }
+
+    # Clean
+    rm -rf in out errors
+    rm -rf ${CUSTOM_MUTATOR_PATH}/__pycache__/
+  } || {
+    ls .
+    ls ${CUSTOM_MUTATOR_PATH}
+    $ECHO "$RED[!] cannot compile the test program or the custom mutator"
+    CODE=1
+  }
+
+  make -C ../examples/custom_mutators clean > /dev/null 2>&1
+  rm -f test-custom-mutator
+} || {
+  $ECHO "$YELLOW[-] no custom mutators in $CUSTOM_MUTATOR_PATH, cannot test"
+  INCOMPLETE=1
+}
+unset CUSTOM_MUTATOR_PATH
+
 $ECHO "$GREY[*] all test cases completed.$RESET"
 test "$INCOMPLETE" = "0" && $ECHO "$GREEN[+] all test cases executed"
 test "$INCOMPLETE" = "1" && $ECHO "$YELLOW[-] not all test cases were executed"