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From:   =?UTF-8?Q?Micha=C5=82_Lowas=2DRzechonek?= 
        <michal.lowas-rzechonek@silvair.com>
Date:   Tue, 28 May 2019 09:28:50 +0200
Message-ID: <CACXRGxx4XO-Rev-nY_ahCqFrCzSeDFDNm8CEyYRm=Et-gZzscA@mail.gmail.com>
Subject: Re: [PATCH BlueZ] mesh: Fix long MIC usage in segmented messages
To:     "Gix, Brian" <brian.gix@intel.com>
Cc:     "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        "jakub.witowski@silvair.com" <jakub.witowski@silvair.com>,
        "Stotland, Inga" <inga.stotland@intel.com>
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Yes, it's fine.

--=20
Micha=C5=82 Lowas-Rzechonek
Lambda Team Leader

Silvair
Jasnog=C3=B3rska 44
31-358 Krakow
POLAND

http://www.silvair.com

pon., 27 maj 2019 o 20:14 Gix, Brian <brian.gix@intel.com> napisa=C5=82(a):
>
> Hi Jakub and Michal,
>
> If you guys are OK with this, this is the version of the patch on long MI=
Cs and segment count I will be
> applying.
>
> On Thu, 2019-05-23 at 10:53 -0700, Brian Gix wrote:
> > From: Jakub Witowski <jakub.witowski@silvair.com>
> >
> > Contrary to the comment, implementation used a 8-byte MIC even if this
> > generated an additional segment.
> > ---
> >  mesh/model.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/mesh/model.c b/mesh/model.c
> > index 034d54496..90bb62db8 100644
> > --- a/mesh/model.c
> > +++ b/mesh/model.c
> > @@ -40,6 +40,9 @@
> >  #include "mesh/util.h"
> >  #include "mesh/model.h"
> >
> > +/* Divide and round to ceiling (up) to calculate segment count */
> > +#define CEILDIV(val, div) (((val) + (div) - 1) / (div))
> > +
> >  struct mesh_model {
> >       const struct mesh_model_ops *cbs;
> >       void *user_data;
> > @@ -451,7 +454,7 @@ static bool msg_send(struct mesh_node *node, bool c=
redential, uint16_t src,
> >
> >       /* Use large MIC if it doesn't affect segmentation */
> >       if (msg_len > 11 && msg_len <=3D 376) {
> > -             if ((out_len / 12) =3D=3D ((out_len + 4) / 12)) {
> > +             if (CEILDIV(out_len, 12) =3D=3D CEILDIV(out_len + 4, 12))=
 {
> >                       szmic =3D true;
> >                       out_len =3D msg_len + sizeof(uint64_t);
> >               }