Re: PIDs limited to 15 significant bits

From: Jeff Epler (jepler@inetnebr.com)
Date: Sat Sep 30 2000 - 08:35:28 EST


On Fri, Sep 29, 2000 at 11:44:42PM +0200, Andries Brouwer wrote:
> There are a few weaknesses that can be exploited using a wraparound.
> With 100 processes/sec that takes 497 days with a 32-bit pid
> and 5 minutes with a 16-bit pid.

Surely the estimate of 100 forks/sec is low. I get 83 forks/sec on
a 486-75 and a Python program, just as an estimate. Besides,
vulnerabilities due to PID wrap should just plain get fixed, if only
because ports to a "lesser" unix might be made.

31- or 32-bit PIDs might be a convenience, but they don't furnish security
against wraparound attacks, they just make them take a little longer to
exploit.

Jeff
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