Fix buffer overflow in SNMP decode
Fix buffer overflow in SNMP decode

snmp_decode_msg didn't update its internal length
variable and could potentially read out-of-bounds
data from the provided buffer. This happened when the
funtion was called with a varbind array bigger than
what the decoded message required.

Signed-off-by: Dariusz Stojaczyk <832a9c81bd9a843f429a5fe668dc0ef19523fb87@gmail.com>

darsto/ber