Re: [PATCH] libceph: use 64-bit arithmetic instead of 32-bit

[Gustavo A. R. Silva]

Hello Ilya,

Quoting Ilya Dryomov <idryomov@xxxxxxxxx>:

> On Wed, Jan 31, 2018 at 6:29 AM, Gustavo A. R. Silva
> <gustavo@xxxxxxxxxxxxxx> wrote:
> > Cast objsetno to u64 in order to give the compiler complete
> > information about the proper arithmetic to use. Notice
> > that this variable is used in a context that expects an
> > expression of type u64 (64 bits, unsigned).
> >
> > The expression objsetno * sc + stripepos is currently
> > being evaluated using 32-bit arithmetic.
> >
> > In general, the use of incorrect arithmetic has security
> > implications.
> >
> > Addresses-Coverity-ID: 200686
> > Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> > ---
> >  net/ceph/osdmap.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> > index 0da27c6..58dc965 100644
> > --- a/net/ceph/osdmap.c
> > +++ b/net/ceph/osdmap.c
> > @@ -2183,7 +2183,7 @@ int ceph_calc_file_object_mapping(struct  
> > ceph_file_layout *layout,
> >         stripepos = bl % sc;
> >         objsetno = stripeno / su_per_object;
> >
> > -       *ono = objsetno * sc + stripepos;
> > +       *ono = (u64)objsetno * sc + stripepos;
> >         dout("objset %u * sc %u = ono %u\n", objsetno, sc,  
> > (unsigned int)*ono);
> >
> >         /* *oxoff = *off % layout->fl_stripe_unit;  # offset in su */
>
> Hi Gustavo,
>
> This (and other u32/u64 issues in this function, is this the only
> warning?) is fixed in my striping v2 work branch.  I wasn't going to
> push that patch separately, but I guess I should post it.

Yeah, this was the only one warning reported by Coverity in this  
particular module.

Thanks
--
Gustavo