Vulnerability in OpenSSL CVE-2016-0799

The internal |fmtstr| function used in processing a "%s" format string in the BIO_*printf functions could overflow while calculating the length of a string and cause an OOB read when printing very long strings. Additionally the internal |doapr_outch| function can attempt to write to an OOB memory location (at an offset from the NULL pointer) in the event of a memory allocation failure. In 1.0.2 and below this could be caused where the size of a buffer to be allocated is greater than INT_MAX. E.g. this could be in processing a very long "%s" format string. Memory leaks can also occur. The first issue may mask the second issue dependent on compiler behaviour. These problems could enable attacks where large amounts of untrusted data is passed to the BIO_*printf functions. If applications use these functions in this way then they could be vulnerable. OpenSSL itself uses these functions when printing out human-readable dumps of ASN.1 data. Therefore applications that print this data could be vulnerable if the data is from untrusted sources. OpenSSL command line applications could also be vulnerable where they print out ASN.1 data, or if untrusted data is passed as command line arguments. Libssl is not considered directly vulnerable. Additionally certificates etc received via remote connections via libssl are also unlikely to be able to trigger these issues because of message size limits enforced within libssl.