diff --git a/testsuites/unittest/fuzz/src/stdlib/realloc_fuzz.c b/testsuites/unittest/fuzz/src/stdlib/realloc_fuzz.c
index 96a6d97e..eebda93e 100644
--- a/testsuites/unittest/fuzz/src/stdlib/realloc_fuzz.c
+++ b/testsuites/unittest/fuzz/src/stdlib/realloc_fuzz.c
@@ -46,6 +46,7 @@ extern int g_iteration;
 void ReallocFuzzTest(void)
 {
     char *source = NULL;
+    char *buf = NULL;
     int c;
 
     printf("Fuzz test in line [%d] realloc start\n", __LINE__);
@@ -59,6 +60,7 @@ void ReallocFuzzTest(void)
     INIT_FuzzEnvironment();
     CreatPrecondForQueue();
     for (int i = 0; i < CYCLE_TOTAL_TIMES; i++) {
+        source = buf;
         hi_watchdog_feed();
         heartbeatPrint(i);
 
@@ -66,10 +68,13 @@ void ReallocFuzzTest(void)
         if ((c <= 0) || (c > TEST_MAX_BUF_LEN)) {
             c = TEST_BUF_LEN;
         }
-        source = (char *)realloc(source, c);
+        buf = (char *)realloc(source, c);
+        if (buf == NULL) {
+            break;
+        }
     }
 
-    if (source == NULL) {
+    if (buf == NULL) {
         free(source);
     }
 
diff --git a/testsuites/unittest/posix/src/string/memory_func_test.c b/testsuites/unittest/posix/src/string/memory_func_test.c
index 6faf65f7..6b553131 100644
--- a/testsuites/unittest/posix/src/string/memory_func_test.c
+++ b/testsuites/unittest/posix/src/string/memory_func_test.c
@@ -270,19 +270,22 @@ LITE_TEST_CASE(PosixMemFuncTestSuite, testOsMemRealloc001, Function | MediumTest
 
         memset(mem, testChar, mlen);
         rlen = rand() % (1024) + mlen;
-        mem = realloc(mem, rlen);
-        TEST_ASSERT_NOT_NULL(mem);
+        char *mem1 = realloc(mem, rlen);
+        if (mem1 == NULL) {
+            free(mem);
+        }
+        TEST_ASSERT_NOT_NULL(mem1);
 
         len = mlen <= rlen ? mlen : rlen;
 
-        data = (char *)mem;
+        data = (char *)mem1;
         for (k = 0; k < len; k++) {
             if (data[k] != testChar) {
                 failure = 1;
             }
         }
 
-        free(mem);
+        free(mem1);
         TEST_ASSERT_EQUAL_INT(failure, 0);
     }
 };