Date: Mon, 20 Oct 1997 18:48:12 +0200 (SAT) From: Graham Wheeler <gram@cdsec.com> To: hackers@freebsd.org Subject: Re: Bug in 2.2.2 Message-ID: <199710201648.SAA11704@cdsec.com>
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>
> can you tell me how to reproduce it within X hours?
> if i remember correctly, it was failing every X hours
> for you. if its statically linked i can hack on
> the shared library and see if i can track this down.
I wrote a small program to exercise the heap and ran it for about ten million
iterations without a problem. Then I decided to add a periodic call to fork(),
as both Midnight Commander and the firewall gateway program both do plenty
of these. When I ran this the O/S panicked almost immediately.
Here is the program:
// A simple program to exercise the heap.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
main()
{
const int vsize = 10000;
char **vector = new char*[vsize];
int i, allocs = 0, deletes = 0;
int seed = time(0);
srand(seed);
for (i = 0; i < vsize; i++) vector[i] = 0;
i = 0;
for (;;)
{
if ((i%100000) == 0)
printf("%d: alloc %d delete %d seed %d\n",
i, allocs, deletes, seed);
if ((i % 100) == 0)
{
int pid = fork();
if (pid == 0) exit(0);
}
int slot = random() % vsize;
if (vector[slot])
{
delete [] vector[slot];
vector[slot] = 0;
deletes++;
}
else
{
int l = (random() % 4096)+1;
vector[slot] = new char[l];
memset(vector[slot], l, l);
allocs++;
}
if (++i < 0) i = 0;
}
}
I hadn't bothered doing any signal catching here; this was quick 'n dirty.
Still, it shouldn't cause a panic. Perhaps there is a connection between
this and the other problem?
> > So it seems there is indeed a bug, either in phkmalloc or in some
> > other FreeBSD library code which uses phkmalloc.
I strongly suspect the latter may be the case, and that the nature of
the bug is such that it affects phkmalloc but not the other malloc.
cheers
gram
--
Dr Graham Wheeler E-mail: gram@cdsec.com
Citadel Data Security Phone: +27(21)23-6065/6/7
Internet/Intranet Network Specialists Mobile: +27(83)-253-9864
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Data Security Products WWW: http://www.cdsec.com/
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