Only send the signal if the pid is a positive value. #593
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What:
Only send the signal if the pid is a positive value.
Why:
Since kb_item_get_int() will return -1 if the key does
not exist. killing with -1 as pid will send the signal system wide.
Apparently the stop signal is received twice, being the second one
sent by a child process, but received after the kb was already cleaned up.
Therefore -1 is received and the kill SIGUSR1 signal reaches other process.
How:
You can test this starting 2 or 3 parallel scans with many hosts. This produces a big amount child process which during stops scans, spread the kill signal to other process. You should be able to stop the scans without problem if this patch is applied.
Checklist: