Snaservr.exe Access Violation In Snpugeti() or Snpuputi()

CAUSE

The Access Violation error message is caused when SNA Server receives an invalid RU from the mainframe. In this case, the invalid RU was sent by the mainframe to indicate an -RSP to an RU it had previously received for a particular LU-LU (Logical Unit) session. The RU indicated that it included Sense Data (SD) since the SD flag was set in its Response Header (RH). The RU was invalid since it did not contain the 4 bytes of sense data that is supposed to be included when the SD flag is set.

When the SNA Server service receives this data, it attempts to extract the sense data from the host response to include it in a Function Management Interface (FMI) Status Acknowledgement that has to be sent to the client emulator to inform the emulator of the detected error. The access violation occurs because the message is too short. It only has 9 bytes of data (6 bytes for the Transmission Header plus 3 bytes for the RH) when it should be 13 bytes in length. The SNA Server service then accesses data beyond the end of the actual message because the last 4 bytes of data are not there. It is the attempt to access memory beyond the end of the message that results in the access violation. The access violation causes the SNA Server service to terminate.