[PATCH] lib/util/idtree.c: fix undefined behaviour by using uint in left-shift

[Ira Cooper]

Reviewed-by: Ira Cooper <ira at samba.org>

Go ahead and push it with whatever else today. :)

-Ira

On Thu, Feb 25, 2016 at 2:31 PM, Jeremy Allison <jra at samba.org> wrote:

> On Thu, Feb 25, 2016 at 04:43:39PM +0100, Aurélien Aptel wrote:
> > Hi,
> >
> > Using negative values (~0 with no suffix is signed and == -1) on the
> > left-side of a left-shift operation is an Undefined Behaviour in C.
> >
> > Please review&push
>
> Good catch ! Revewied-by: Jeremy Allison <jra at samba.org>
>
> Can I get a second Team reviewer ?
>
> > --
> > Aurélien Aptel / SUSE Labs Samba Team
> > GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> > SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
> > GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG
> > Nürnberg)
>
> > From f6e5d8b07e3a63b461e13ebe06b5897f5079c8ea Mon Sep 17 00:00:00 2001
> > From: Aurelien Aptel <aaptel at suse.com>
> > Date: Thu, 25 Feb 2016 13:58:01 +0100
> > Subject: [PATCH 3/3] lib/util/idtree.c: fix UB by using uint in
> left-shift
> >
> > Using negative values on the left-side of a left-shift operation is an
> > Undefined Behaviour in C.
> >
> > Signed-off-by: Aurelien Aptel <aaptel at suse.com>
> > ---
> >  lib/util/idtree.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/util/idtree.c b/lib/util/idtree.c
> > index e2cfcc5..72266a6 100644
> > --- a/lib/util/idtree.c
> > +++ b/lib/util/idtree.c
> > @@ -289,7 +289,7 @@ static void *_idr_find(struct idr_context *idp, int
> id)
> >        * present.  If so, tain't one of ours!
> >        */
> >       if (n + IDR_BITS < 31 &&
> > -         ((id & ~(~0 << MAX_ID_SHIFT)) >> (n + IDR_BITS))) {
> > +         ((id & ~(~0U << MAX_ID_SHIFT)) >> (n + IDR_BITS))) {
> >               return NULL;
> >       }
> >
> > --
> > 2.1.4
> >
>
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>