A fix is available
APAR status
Closed as program error.
Error description
A DVIPA is distributed with sysplexports enabled. A timing sequence exists with a connection attempting to connect to the DVIPA on a non-distributed port and the DVIPA listener being started multiple times. This can cause an incorrect entry to be left in the VCRT hash table pointing to freed storage. This can cause abends attempting to free the storage twice or reference storage. . ADDITIONAL SYMPTOMS: 1) EZBXFGP2(HIP61D0 11.090)+018B1C S0C4 2) EZBXFUT5(HIP61D0 11.090)+0019DE S4C5/77C10402 EZBXFMS6 ABEND4C5 77BD0402 EZBXFGP2 ABEND4C5 773B0402 CRHTE Bad Ref Ct Reference Count 3) EZBXFTMR(UK80455 125)+000718 S0C4/00000011 . VERIFICATION STEPS: 1) VCRT entry will point to freed storage or storage for a different entry. Netstat VCRT may show the same connection twice. 2) TCPIPCS XCF report may show a CRHTE with an IFR of In Flight Recorder Area (oldest to newest): IFR24:RTE_SYN IFR23:MERGE_PENDING IFR09:SRV_PASV IFR0D:INC_NUMTERMCONNS 3) Netstat VCRT will not have an entry for a listener on a sysplexports DVIPA, but the hash table key in the HASE will have the correct key.
Local fix
If listener is started on a configured port which does not change, code that port on the VIPADISTRIBUTE statement. This will prevent the SYSPLEXPORTS logic from being used for connections to that port.
Problem summary
**************************************************************** * USERS AFFECTED: All users of the IBM Communications Server * * for z/OS Version 1 Release 13 IP: * * Distributed DVIPA * **************************************************************** * PROBLEM DESCRIPTION: Abend S0C4 in EZBXFUT3 using * * SYSPLEXPORTS DVIPA. * **************************************************************** * RECOMMENDATION: * **************************************************************** A timing scenario exists during which connections attempted to a distributed DVIPA using sysplexports may reference storage after it has been freed and cause an abend. The problem can be summarized as follows: 1. A connection is attempted to DVIPA A port B and the SYN request is queued at the sysplex distributor. 2. A listener is not yet started for DVIPA A port B and the connection is reset after approximately 15 seconds. 3. A listener is started on the DVIPA target and notifies the distributor it can accept connections to DVIPA A port B. 4. The listener closes on the DVIPA target and notifies the distributor it is not accepting connections on DVIPA A port B. 5. A listener is started again on the DVIPA target and notifies the distributor it can accept connections to DVIPA A port B. If steps 1 through 5 occur within several minutes, TCP incorrectly frees storage at the distributor related to the target DVIPA A Port B, but maintains a pointer to the freed storage. 6. A connection is attempted to DVIPA A port B and and at the sysplex distributor the pointer to the freed storage is used and causes an abend. +-------------------------------------------------------------+ + Please check our Communications Server for OS/390 homepages + + for common networking tips and fixes. The URL for these + + homepages can be found in Informational APAR II11334. + +-------------------------------------------------------------+
Problem conclusion
TCPIP has been modified to not free the referenced storage. * Cross Reference between External and Internal Names
Temporary fix
Comments
APAR Information
APAR number
PM78535
Reported component name
TCP/IP V3 MVS
Reported component ID
5655HAL00
Reported release
1D0
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2012-12-05
Closed date
2013-01-02
Last modified date
2013-06-21
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK90704
Modules/Macros
EZBCTFME EZBITTRC EZBXFACI EZBXFHSH EZBXFUTL EZBXFUT3 EZBX6ACI EZBX6HSH EZBX6UT3
Fix information
Fixed component name
TCP/IP V3 MVS
Fixed component ID
5655HAL00
Applicable component levels
R1D0 PSY UK90704
UP13/02/02 P F302
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
21 June 2013