ASA-2018-00020 – curl: warning message out-of-bounds read

curl contains a heap out-of-bounds read vulnerability. The command line tool has a generic function for displaying warning and informational messages to stderr for various situations. For example if an unknown command line argument is used, or passed to it in a "config" file. This display function formats the output to wrap at 80 columns. The wrap logic is however flawed, so if a single word in the message is itself longer than 80 bytes the buffer arithmetic calculates the remainder wrong and will end up reading behind the end of the buffer. This could lead to information disclosure or crash.