libmodplug: two code execution vulnerabilities

From the Red Hat bugzilla entry:

It was reported [1],[2] that libmodplug suffers from two flaws when parsing ABC files:

1) An error within the "abc_MIDI_drum()" function (src/load_abc.cpp) can be exploited to cause a buffer overflow via a specially crafted ABC file.

2) An integer overflow within the "abc_set_parts()" function (src/load_abc.cpp) can be exploited to corrupt heap memory via a specially crafted ABC file.

Successful exploitation of the vulnerabilities may allow execution of arbitrary code.