# Use After Free

**Example 1: C**

**Vulnerable Code:**

```c
cCopy codechar *ptr = malloc(10);
free(ptr);
strcpy(ptr, "data");
```

**Reason for vulnerability:** Using memory after it has been freed, leading to undefined behavior.

**Fixed Code:**

```c
cCopy codechar *ptr = malloc(10);
strcpy(ptr, "data");
free(ptr);
ptr = NULL;
```

**Reason for fix:** Set the pointer to `NULL` after freeing it to prevent use after free.

**Example 2: C++**

**Vulnerable Code:**

```cpp
cppCopy codeint *ptr = new int[10];
delete[] ptr;
ptr[0] = 1;
```

**Reason for vulnerability:** Using memory after it has been freed, leading to undefined behavior.

**Fixed Code:**

```cpp
cppCopy codeint *ptr = new int[10];
delete[] ptr;
ptr = nullptr;
```

**Reason for fix:** Set the pointer to `nullptr` after deleting it to prevent use after free.