snd_seq_ev_set_ump_data() stack smashing

[GitHub issues - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-lib issue #346 was opened from symdeb:

snd_seq_ev_set_ump_data(&umpev, buffer, len); 

When called with len > 4 causes stack smashing. 
A ump messages is maximum four  32bit values.
Proposal solution, return error when len > 4 ?

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/346
Repository URL: https://github.com/alsa-project/alsa-lib