Symptoms

In some cases AVR tries to release the same memory area twice, which leads to memory corruption and tmm crash.

Impact

Traffic disrupted while tmm restarts.

Conditions

There are 2 configurations that can lead to it: 1. Application Dos is used. 2. AVR is used with the option of Max Statistics turned on. In both cases, HTTP responses should be compressed, and some timing issue with regards to compression activity running in parallel to the payload being transferred, can lead to this situation.

Workaround

If Application Dos is used - there is no workaround. If AVR is used, then disabling the option of "Max Statistics" solves the problem. Run the command: tmsh modify sys db md.enablemaxandglobalhttpstats value 0

Fix Information

Fixed an Application DoS/AVR issue that caused the double release of memory, and possible memory corruption.

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips