NULL ptr dereferences found with Calysto static checker

[Domagoj Babic]

Please see

localtime/gmtime in
http://www.gnu.org/software/libc/manual/html_mono/libc.html.gz

On 6/20/07, Gert Doering <gert at greenie.muc.de> wrote:
> Hi,
>
> On Wed, Jun 20, 2007 at 11:06:31AM -0700, Domagoj Babic wrote:
> > I've ran my static checker Calysto on openssh and found the following bug:
> >
> > Possible NULL-ptr deref (vc536):
> > @/work/benchmarks/SOURCES/openssh-4.6p1/moduli.c:173
> > + ptr gtm returned from gmtime dereferenced without checking (gmtime can
> > return NULL).
>
> Now this surprises me a bit - I've checked FreeBSD 4 and 6 man pages,
> and neither mentions that the return ptr could be NULL.
>
> Checking older SVR3 man pages, I can see the reason:
>
> --------------- quote ---------------
>  Note
>
>     The return values for ctime, localtime and gmtime point to static data
>     whose content is overwritten by each call.
> --------------- quote ---------------
>
> So under which circumstances can it be NULL?
>
> gert
>
> --
> USENET is *not* the non-clickable part of WWW!
>                                                            //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
>


-- 
        Domagoj Babic

        http://www.domagoj.info/
        http://www.calysto.org/