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Netscaler VPX 12.57.19 Memory Leak

Jens Dellner

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I observe a memory leak on our Netscalers VPX with 12.57.19.


nsconmsg -K newnslog -d memstats shows an increase of:


MEMPOOL             MaxAllowd           CurAlloc                  ErrLmtFailed   ErrAllocFailed  ErrFreeFailed
MEM_TBUF           4294967295     572522496(13.33%  14.32%)          0                0            0
MEM_TBUF           4294967295     689963008(16.06%  17.26%)          0                0            0

MEM_TBUF           4294967295     719323136(16.75%  18.00%)          0                0            0


Name             CurAllocd            CurFree        PgAllocd     PgAllocFailed
BM512            1072890              1906           262 (13.7%)                     0
BM512            1302210              1567           318 (16.7%)                     0

BM512            1359540              3627           332 (17.4%)                     0


I have to failover every few days and reboot the primary appliance to flush the memory. A similar problem was described in https://support.citrix.com/article/CTX217918 . They write "Every handshake containing the AES-GCM cipher, causes the MEM_TBUF to increase." but don´t explain how they identified it. So i don´t know if it is the same problem than mine. I had no success with unbinding the AES-GCM ciphers.


Does anybody know what MEM_TBUF and BM512 describes and how to troubleshoot it further? Thank you!

Best Regards,

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Problem: Memory Leak after using SSL Ciphers "TLS1.2-ECDHE-RSA-CHACHA20-POLY1305" and "TLS1.2-DHE-RSA-CHACHA20-POLY1305".


Workaround: Remove both Ciphers from your custom cipher Groups.


This bug will be fixed in the upcoming Netscaler Version 12.1 and the Engineering Team has been asked to backport this fix in 12.0 also. (by Citrix Escalation Engineer)

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