Bug ID 760680: TMSH may utilize 100% CPU (single core) when set to be a process group leader and SSH session is closed.

Last Modified: May 23, 2019

Bug Tracker

Affected Product:  See more info
BIG-IP TMOS(all modules)

Known Affected Versions:
14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.4, 14.1.0.5

Opened: Mar 07, 2019
Severity: 4-Minor

Symptoms

TMSH does not correctly handle absence of input stream after closing interactive SSH session and remains active in an infinite loop using 100% CPU.

Impact

One CPU core is utilized in 100% by runaway TMSH process.

Conditions

If TMSH is a process group leader, it will not be killed when the parent shell is terminated upon SSH session close. It is a rare case as TMSH would have to be deliberately promoted to a process group leader e.g. with setsid command. Usually the shell process is a group leader and, when it is terminated upon SSH session close, it will kill its child processes including TMSH.

Workaround

TMSH should not be intentionally promoted to a process group leader. Abandoned TMSH process can be safely killed with "killall tmsh" command.

Fix Information

None

Behavior Change