...
The affects of not following this recommendation are best demonstrated by an actual vulnerability. Freeing memory in different modules resulted in a vulnerability in MIT Kerberos 5 MITKRB5-SA-2004-002 . The problem is was that the MIT Kerberos 5 code contains contained error-handling logic, which frees freed memory allocated by the ASN.1 decoders if pointers to the allocated memory are were non-null. However, if a detectable error occursoccured, the ASN.1 decoders themselves free freed the memory that they have had allocated. When some library functions receive received errors from the ASN.1 decoders, they also attempt attempted to free, causing a double-free vulnerability.
...