Fix process tracking confusion, inadvertent proc table modification #236
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For non-`execve*` syscalls, we consult the process table to find out whether we have seen the process before or whether a new entry needs to be added to the process table. The process table lookup was done using `.get_or_retrieve` which might modify the process table by filling in a missing entry from `/proc/$PID/` and subsequently returning a misleading result that contained only a process `START_TIME` instead of an `EVENT_ID`. This problem would cause the event ID to be ignored and break process label inheritance, particularly in double-`fork` scenarios common in shell scripts. Since a race can't be avoided in accessing `/proc`, reproducing this bug was quite unreliable. To fix this, we simply use `.get_pid` which will not modify the process table for its lookup.
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For non-
execve*syscalls, we consult the process table to find out whether we have seen the process before or whether a new entry needs to be added to the process table.The process table lookup was done using
.get_or_retrievewhich might modify the process table by filling in a missing entry from/proc/$PID/and subsequently returning a misleading result that contained only a processSTART_TIMEinstead of anEVENT_ID.This problem would cause the event ID to be ignored and break process label inheritance, particularly in double-
forkscenarios common in shell scripts. Since a race can't be avoided in accessing/proc, reproducing this bug was quite unreliable.To fix this, we simply use
.get_pidwhich will not modify the process table for its lookup.