[dpdk-dev] [PATCH v1] metrics: fix potential missing NULL termination

[Bruce Richardson]

On Tue, Feb 20, 2018 at 02:50:01PM +0000, Remy Horton wrote:
> Fixes a potential memory overrun detected by Coverity.
> This overrun cannot currently happen in practice because
> rte_metrics_reg_names() explicitly forces the last name
> character to be a NULL terminator. This patch adds the
> same enforcement to rte_metrics_get_names() in order to
> correct the warning.
> 
> Coverity issue: 143434
> Fixes: 349950ddb9c5 ("metrics: add information metrics library")
> 
> Signed-off-by: Remy Horton <remy.horton at intel.com>
> ---
>  lib/librte_metrics/rte_metrics.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_metrics/rte_metrics.c b/lib/librte_metrics/rte_metrics.c
> index 556ae1b..958ef3d 100644
> --- a/lib/librte_metrics/rte_metrics.c
> +++ b/lib/librte_metrics/rte_metrics.c
> @@ -214,10 +214,15 @@ rte_metrics_get_names(struct rte_metric_name *names,
>  			rte_spinlock_unlock(&stats->lock);
>  			return return_value;
>  		}
> -		for (idx_name = 0; idx_name < stats->cnt_stats; idx_name++)
> +		for (idx_name = 0; idx_name < stats->cnt_stats; idx_name++) {
>  			strncpy(names[idx_name].name,
>  				stats->metadata[idx_name].name,
>  				RTE_METRICS_MAX_NAME_LEN);
> +		/* Enforce NULL-termination. The source string should already
> +		 * be NULL-terminated, so this is to quieten lint checks..
> +		 */
> +		names[idx_name].name[RTE_METRICS_MAX_NAME_LEN - 1] = '\0';
> +		}
>  	}

Again, I think the better fix is to replace strncpy with snprintf which
will guarantee the null termination, unlike strncpy which is nasty that
way.

/Bruce