Re: gawk: other double free(_wstr)

[Aharon Robbins]

Zeroizing n in rebuild record won't hurt anything. I'm not sure it's
necessary either, though.

More and more I'm starting to lean towards the idea of just having getnode()
do a memset(n, '\0', sizeof(NODE)) and then not having to worry.

I will consider this patch a bit more.

Thanks,

Arnold

> Date: Fri, 12 Jan 2007 12:46:39 +0100
> From: Karel Zak <address@hidden>
> Subject: Re: gawk: other double free(_wstr)
> To: address@hidden
>
> On Fri, Jan 12, 2007 at 11:46:58AM +0100, Karel Zak wrote:
> > 
> >> 
> >  The problem is probably somewhere around rebuild_record(), because it
> >  calls unref() (which correctly deallocates wstptr), but then the 
> >  rebuild_record() reassigns deallocated wstptr back to fields_arr[i]:
> > 
> >      n->stptr = cops;
> >      unref(fields_arr[i]);   <--- free( fields_arr[i]->wstptr )
> >      fields_arr[i] = n;      <--- deallocated wstptr is back 
> >  
> >  I'm not sure how correctly fix the problem, maybe the "n"
> >  should be without WSTRCUR flag before reassigning to fields_arr[i]. 
> > 
> >      n->flags &= ~(MALLOC|TEMP|PERM|STRING|CURSTR|WCURSTR);
> >                                           ^^^^^^^^^^^^^^^
>
>  BTW, in the original Aharon's patch
>  
>     Fri Mar 10 06:28:23 2006  Arnold D. Robbins  <address@hidden>
>  
>  was:
>
>                       n->stptr = cops;
> +                     free_wstr(n);            
>                       unref(fields_arr[i]);
>                       fields_arr[i] = n;
>
>  (but there wasn't free_wstr() in unref())
>
>  I think the "n" should be still zeroized in rebuild_record() :
>
>             n->stptr = cops;
>             unref(fields_arr[i]);
> +           n->wstptr = NULL;
> +           n->wstlen = 0;
> +           n->flag &= ~WCURSTR;
>             fields_arr[i] = n;
>
>
>   Karel
>
>
> -- 
>  Karel Zak  <address@hidden>
>
>
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