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

Greg KH
2016-06-02T16:24:26Z

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?

thanks,

greg k-h