[ovs-dev] [PATCH 2/2] netdev-dpdk: fix snprintf call

[Ben Pfaff]

On Thu, Jun 14, 2018 at 05:11:39PM -0400, Aaron Conole wrote:
> Ben Pfaff <blp at ovn.org> writes:
> 
> > On Wed, Jun 13, 2018 at 03:43:04PM -0400, Aaron Conole wrote:
> >> lib/netdev-dpdk.c: In function :
> >> lib/netdev-dpdk.c:2865:49: warning:  output may be truncated before the last format character [-Wformat-truncation=]
> >>         snprintf(vhost_vring, 16, "vring_%d_size", i);
> >>                                                 ^
> >> lib/netdev-dpdk.c:2865:9: note:  output between 13 and 17 bytes into a destination of size 16
> >>         snprintf(vhost_vring, 16, "vring_%d_size", i);
> >>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> 
> >> Since vring_num is 16 bits, the largest value ever would only be 17 bytes,
> >> including the terminating nul.  Stretch it to 18 bytes (as a precaution
> >> against a signed value, which again would never happen).
> >> 
> >> Signed-off-by: Aaron Conole <aconole at redhat.com>
> >> ---
> >>  lib/netdev-dpdk.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> >> index 2e2f568b8..e75943bb2 100644
> >> --- a/lib/netdev-dpdk.c
> >> +++ b/lib/netdev-dpdk.c
> >> @@ -2859,7 +2859,7 @@ netdev_dpdk_vhost_user_get_status(const struct netdev *netdev,
> >>  
> >>      for (int i = 0; i < vring_num; i++) {
> >>          struct rte_vhost_vring vring;
> >> -        char vhost_vring[16];
> >> +        char vhost_vring[18];
> >>  
> >>          rte_vhost_get_vhost_vring(vid, i, &vring);
> >>          snprintf(vhost_vring, 16, "vring_%d_size", i);
> >
> > Thanks for the improvement.
> >
> > Instead of calculating at all, I think it would be less error-prone to
> > avoid it, something like this:
> >
> > diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> > index fd496592ba56..040b17f8a34a 100644
> > --- a/lib/netdev-dpdk.c
> > +++ b/lib/netdev-dpdk.c
> > @@ -2883,11 +2883,9 @@ netdev_dpdk_vhost_user_get_status(const struct netdev *netdev,
> >  
> >      for (int i = 0; i < vring_num; i++) {
> >          struct rte_vhost_vring vring;
> > -        char vhost_vring[18];
> > -
> > -        rte_vhost_get_vhost_vring(vid, i, &vring);
> 
> Just one thing... should you submit this (or merge it) - don't drop this
> line :-)

I was hoping that you would submit it, would you mind?