Re: [PATCH] sched: fix integer handling issue

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 22 Feb 2022 15:13:53 +0100
Morten Brørup <mb@smartsharesystems.com> wrote:

> > From: Megha Ajmera [mailto:megha.ajmera@intel.com]
> > Sent: Tuesday, 22 February 2022 14.19
> > 
> > Masking of core mask was incorrect. Instead of using 1U for shifting,
> > it
> > should be using 1LU as the result is assigned to uint64.
> > 
> > CID 375859: Potentially overflowing expression "1U << app_main_core"
> > with
> > type "unsigned int" (32 bits, unsigned) is evaluated using 32-bit
> > arithmetic,
> > and then used in a context that expects an expression of type
> > "uint64_t"
> > (64 bits, unsigned).
> > 
> > Coverity issue: 375859
> > 
> > Signed-off-by: Megha Ajmera <megha.ajmera@intel.com>
> > ---
> >  examples/qos_sched/args.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/examples/qos_sched/args.c b/examples/qos_sched/args.c
> > index 10ca7bea61..44f2f5640e 100644
> > --- a/examples/qos_sched/args.c
> > +++ b/examples/qos_sched/args.c
> > @@ -433,7 +433,7 @@ app_parse_args(int argc, char **argv)
> >  			return -1;
> >  		}
> >  	}
> > -	app_used_core_mask |= 1u << app_main_core;
> > +	app_used_core_mask |= 1lu << app_main_core;  
> 
> Still wrong on 32 bit platforms, where long unsigned int is still 32 bits.
> 
> Use this instead:
> app_used_core_mask |= RTE_BIT64(app_main_core);

DPDK now supports > 64 lcores. So all code using/assuming a 64 bit mask is broken.