This indicates an attempt to exploit a Buffer Overflow vulnerability in Samba.
The vulnerability is due to the "receive_smb_raw()" function's failure to properly bounds check user supplied data when processing SMB packets. A remote attacker may be able to exploit this by sending overly large SMB packets.
Samba 3.0 through 3.0.29
System Compromise: Remote attackers may gain control of vulnerable systems.
Denial of Service.
Apply the latest update from the vendor: