Re: [Qemu-devel] [PATCH v3 1/4] numa: Fix off-by-one error at MAX_CPUMASK_BITS check

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 12 Feb 2015 15:50:32 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> Fix the CPU index check to ensure we don't go beyond the size of the
> node_cpu bitmap.
> 
> CPU index is always less than MAX_CPUMASK_BITS, as documented at
> sysemu.h:
> 
> > The following shall be true for all CPUs:
> >   cpu->cpu_index < max_cpus <= MAX_CPUMASK_BITS
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  numa.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/numa.c b/numa.c
> index 0d15375..41e496b 100644
> --- a/numa.c
> +++ b/numa.c
> @@ -76,9 +76,9 @@ static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error **errp)
>      }
>  
>      for (cpus = node->cpus; cpus; cpus = cpus->next) {
> -        if (cpus->value > MAX_CPUMASK_BITS) {
> +        if (cpus->value >= MAX_CPUMASK_BITS) {
>              error_setg(errp, "CPU number %" PRIu16 " is bigger than %d",
> -                       cpus->value, MAX_CPUMASK_BITS);
> +                       cpus->value, MAX_CPUMASK_BITS - 1);
>              return;
>          }
>          bitmap_set(numa_info[nodenr].node_cpu, cpus->value, 1);