CVE-2019-17042

An issue was discovered in Rsyslog v8.1908.0.
contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for
Cisco log messages. The parser tries to locate a log message delimiter (in
this case, a space or a colon), but fails to account for strings that do
not satisfy this constraint. If the string does not match, then the
variable lenMsg will reach the value zero and will skip the sanity check
that detects invalid log messages. The message will then be considered
valid, and the parser will eat up the nonexistent colon delimiter. In doing
so, it will decrement lenMsg, a signed integer, whose value was zero and
now becomes minus one. The following step in the parser is to shift left
the contents of the message. To do this, it will call memmove with the
right pointers to the target and destination strings, but the lenMsg will
now be interpreted as a huge value, causing a heap overflow.

Bugs

• <https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942065&gt;

Notes