Libpcap has a buffer overflow. Libpcap uses strcpy to copy a 
device (interface-name) to ifreq.ifr_name (16-byte buffer).
The buffer can be overflowed if the program using libpcap passes
userdefined 'device' to pcap_open_live.
Test: tcpdump -i `perl -e "print 'A'x1000"`

This is not big problem unless someone has made a setuid libpcap program.

I'm attaching a patch that seems to fix this.

(Also it looks like might pcap-dlpi.c suffers from similar problem).