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To: freebsd-hackers@freebsd.org
Subject: Re: netstat: kvm_read: Bad address
References: <199710242055.PAA08603@elvis.mu.org>
From: Dave Marquardt <marquard@zilker.net>
Date: 24 Oct 1997 17:11:09 -0500
In-Reply-To: Paul Saab's message of "Fri, 24 Oct 1997 15:55:45 -0500 (CDT)"
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Paul Saab <paul@mu.org> writes:
> and find the bug.  Now today I got this while doing a netstat on
> another machine with exactly the same hardware configuration as
> the one which had the kernel panic but it is running 2.2.5-RELEASE.
> 
> 
> Active Internet connections
> Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
> tcp        0      0  themaneater.com.http   204.184.83.7.1976      ESTABLISHED
> tcp        0   8398  themaneater.com.http   204.184.83.7.1975      ESTABLISHED
> tcp        0   5650  themaneater.com.http   204.184.83.7.1974      ESTABLISHED
> tcp        0      0  themaneater.com.http   208.196.245.66.2658    ESTABLISHED
> tcp        0      0  themaneater.com.http   208.196.245.66.2657    ESTABLISHED
> tcp        0      0  themaneater.com.ftp-da Mizzou-AS6-17.mi.1232  TIME_WAIT
> tcp      361 -266160568  themaneater.com.http   16.211.65.241.2656     -264201400
> tcp        0 -264546048  128.204.64.241.16625   144.105.65.241.39147   CLOSED
> netstat: kvm_read: Bad address
> ???
> udp        0      0  elvis.4724             elvis.domain          
> udp        0      0  localhost.domain       *.*                   
> udp        0      0  elvis.domain           *.*                   

You'll see this on lots of BSD-based systems.  netstat reads the items
on the tcb (TCP PCB) list one at a time from kernel memory, and the
list has changed while you were reading it.  No big deal, just a
little annoying.  To fix it would be painful, I think.

-Dave