Re: [PATCH] IB/core: Fix bit curruption in ib_device_cap_flags structure

Greg KH
2016-06-02T16:52:38Z

On Thu, Jun 02, 2016 at 07:41:10PM +0300, Max Gurtovoy wrote:
>
>
> On 6/2/2016 7:24 PM, Greg KH wrote:
> > On Thu, Jun 02, 2016 at 12:28:05PM +0300, Max Gurtovoy wrote:
> > > ib_device_cap_flags 64-bit expansion caused caps overlapping
> > > and made consumers read wrong device capabilities. For example
> > > IB_DEVICE_SG_GAPS_REG was falsely read by the iser driver causing
> > > it to use a non-existing capability. This happened because signed
> > > int becomes sign extended when converted it to u64. Fix this by
> > > casting IB_DEVICE_ON_DEMAND_PAGING enumeration to ULL.
> > >
> > > Fixes: fb532d6a79b9 ('IB/{core, ulp} Support above 32 possible device capability flags')
> > > Reported-by: Robert LeBlanc <robert-4JaGZRWAfWbajFs6igw21g@public.gmane.org>
> > > Cc: Stable <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> #[v4.6+]
> > > Acked-by: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
> > > Signed-off-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > > Signed-off-by: Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > > ---
> > > include/rdma/ib_verbs.h | 2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> > > index 432bed5..c97357b 100644
> > > --- a/include/rdma/ib_verbs.h
> > > +++ b/include/rdma/ib_verbs.h
> > > @@ -217,7 +217,7 @@ enum ib_device_cap_flags {
> > > IB_DEVICE_CROSS_CHANNEL = (1 << 27),
> > > IB_DEVICE_MANAGED_FLOW_STEERING = (1 << 29),
> > > IB_DEVICE_SIGNATURE_HANDOVER = (1 << 30),
> > > - IB_DEVICE_ON_DEMAND_PAGING = (1 << 31),
> > > + IB_DEVICE_ON_DEMAND_PAGING = (1ULL << 31),
> > > IB_DEVICE_SG_GAPS_REG = (1ULL << 32),
> > > IB_DEVICE_VIRTUAL_FUNCTION = ((u64)1 << 33),
> > > IB_DEVICE_RAW_SCATTER_FCS = ((u64)1 << 34),
> >
> > Why not just use the BIT() and BIT_ULL() macros instead of "open coding"
> > these?
>
> Good idea. do you think it will be a good idea to set all the elements in
> this ib_device_cap_flags enum to BIT_ULL() in this patch ? to have 1 style
> instead of many ?

Yes.