Date: Sun, 24 Mar 2002 17:35:16 -0500 From: Jake Burkholder <jake@locore.ca> To: Andrew Griffiths <nullptr@tasmail.com> Cc: security@FreeBSD.ORG Subject: Re: page fault. Message-ID: <20020324173516.V90182@locore.ca> In-Reply-To: <200203242143.g2OLh4523143@franklin.nt.tas.gov.au>; from nullptr@tasmail.com on Mon, Mar 25, 2002 at 08:43:05AM %2B1100 References: <200203242143.g2OLh4523143@franklin.nt.tas.gov.au>
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Apparently, On Mon, Mar 25, 2002 at 08:43:05AM +1100,
Andrew Griffiths said words to the effect of;
> Hello,
>
> While testing some code to show the stack ranges on systems, I noticed that freebsd wouldn't segfault when it accessed memory below esp, or the stack bottom.
>
> Not sure whether its a problem, but I think its worth noting.
You mean numerically higher addresses than %esp? Like this?
int
main(void)
{
volatile int *v;
int a;
for (v = &a;; v++)
printf("%p: %#x\n", v, *v);
}
I depends how far you go. A bunch of stuff is copied out to the top of
the stack by the kernel so you have some slush to work through. In either
direction you'll eventually get a segfault (sigbus in the above case because
you run into kernel address space).
>
> Andrew Griffiths
>
> --
> www.tasmail.com
>
>
>
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