Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Dec 16, 2011 at 1:21 AM, Greg Smith <greg@2ndquadrant.com> wrote:
>> ... If you assume someone can run through all the
>> PIDs between those checks and the kill, the system is already broken that
>> way.
> From a theoretical point of view, I believe it to be slightly
> different. If a superuser sends a kill, they will certainly be
> authorized to kill whatever they end up killing, because they are
> authorized to kill anything. On the other hand, the proposed patch
> would potentially result - in the extremely unlikely event of a
> super-fast PID wraparound - in someone cancelling a query they
> otherwise wouldn't have been able to cancel.
> In practice, the chances of this seem fairly remote.
I think this argument is bogus: if this is a real issue, then no use of
kill() anytime, by anyone, is safe. In practice I believe that Unix
systems avoid recycling PIDs right away so as to offer some protection.
regards, tom lane