Off-by-one error in epan/dissectors/packet-gsm_abis_oml.c in the GSM A-bis OML dissector in Wireshark 1.12.x before 1.12.10 and 2.x before 2.0.2 allows remote attackers to cause a denial of service (buffer over-read and application crash) via a crafted packet that triggers a 0xff tag value.