There implementation assumed that arg is null terminated. Due to
the ContentLineAnalyzer wrongly being in plain delivery mode, this
assumption was violated. It shouldn't happen anymore, but protect
from this anyhow.
OSS-Fuzz found that providing an invalid BDAT line would tickle an
assert in UpdateState(). The BDAT state was never initialized, but
within UpdateState() that was expected.
This also removes the AnalyzerViolation() call for bad BDAT commands
and instead raises a weird. The SMTP analyzer is very lax and not triggering
the violation allows to parse the server's response to such an invalid
command.
PCAP files produced by a custom Python SMTP client against Postfix.