Re: heap overflow in procmail

[Rich Felker <dalias () libc org>]

On Wed, Sep 03, 2014 at 11:52:11AM -0700, Tavis Ormandy wrote:
> I noticed a heap overflow in procmail when parsing addresses with
> unbalanced quotes. I encountered this by accident when trying to
> organize a large usenet archive, this post to rec.arts.poems causes
> formail to crash.
>
> https://groups.google.com/forum/message/raw?msg=alt.arts.poetry.comments/DCuLO3qzovI/CZk15MlfqNkJ
>
> I've attached an mbox for reference.
>
> $ formail -s < mbox > /dev/null
> *** Error in `formail': free(): invalid next size (fast): 0x00007f103784a080 ***
> Segmentation fault (core dumped)
> $ rpm -q procmail
> procmail-3.22-33.fc20.x86_64
>
>
> It looks like the fix is
>
> --- formisc.c 2013-08-04 00:13:33.000000000 -0700
> +++ formisc.c 2014-09-03 11:42:25.986002396 -0700
> @@ -84,12 +84,11 @@
>   case '"':*target++=delim='"';start++;
>        }
>       ;{ int i;
> - do
> + while(*start)
>     if((i= *target++= *start++)==delim) /* corresponding delimiter? */
>        break;
>     else if(i=='\\'&&*start)    /* skip quoted character */
>        *target++= *start++;
> - while(*start); /* anything? */
>        }
>       hitspc=2;
>     }

Unless I'm misunderstanding your report, the problem is in the formail
utility which comes with procmail, not procmail itself. This should be
clarified in the title of the vuln, perhaps as "heap overflow in
procmail's formail utility" rather than "heap overflow in procmail".

Rich