Date: Sat, 20 Sep 2008 02:06:02 -0700 (PDT) From: Unga <unga888@yahoo.com> To: Giorgos Keramidas <keramida@ceid.upatras.gr> Cc: freebsd-questions@freebsd.org Subject: Re: Segmentation fault when free Message-ID: <958402.1645.qm@web57004.mail.re3.yahoo.com> In-Reply-To: <87bpyj9qi9.fsf@kobe.laptop>
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--- On Sat, 9/20/08, Giorgos Keramidas <keramida@ceid.upatras.gr> wrote:
> > 1. This clearly shows my program is trying to free a
> memory that has
> > not been allocated. How it could have happened?
>
> Aha. This looks remarkably like an address in the runtime
> stack. It
> usually happens when you have a function that returns the
> address of a
> 'local' variable, instead of a newly allocated heap
> area, i.e.:
>
> char *
> function(void)
> {
> char buffer[100];
>
> return buf;
> }
>
This problem happens very early stage of my program. Its the very first free() develops a problem.
I checked again, up to the this problematic free(), functions return newly allocated strings properly:
char *f( )
{
char *newstr = NULL;
:
newstr = (char *) malloc(p - sp + 1);
if (newstr == NULL)
return NULL;
:
return newstr;
}
Can a yet not executed wrong free() elsewhere cause a problem of this nature?
Best regards
Unga
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