[dpdk-dev] [PATCH] xstats: fix behavior when a null array is provided

[Van Haaren, Harry]

> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier Matz
> Subject: [dpdk-dev] [PATCH] xstats: fix behavior when a null array is provided
> 
> Coverity reports an issue in ethdev:
> 
>   *** CID 124562:  Null pointer dereferences  (FORWARD_NULL)
>   /lib/librte_ether/rte_ethdev.c: 1518 in rte_eth_xstats_get()
>   1512
>   1513		/* global stats */
>   1514     	for (i = 0; i < RTE_NB_STATS; i++) {
>   1515     	    stats_ptr = RTE_PTR_ADD(&eth_stats,
>   1516
>   rte_stats_strings[i].offset);
>   1517			val = *stats_ptr;
>   >>>     CID 124562:  Null pointer dereferences  (FORWARD_NULL)
>   >>>     Dereferencing null pointer "xstats".
>   1518     	      	   snprintf(xstats[count].name,
>   sizeof(xstats[count].name),
>   1519				"%s", rte_stats_strings[i].name);
>   1520     			      xstats[count++].value = val;
>   1521     			      }
>   1522
>   1523		/* per-rxq stats */
> 
> If a user calls rte_eth_xstats_get(portid, NULL, n) with n != 0,
> it may result in a crash. Although the API documentation says that
> n is the size of the table and xstats can be NULL if n == 0, we
> can add an additional check here to make Coverity happy.
> 
> In that case, the return value is the same than when n == 0 is
> passed, it returns the number of statistics.
> 
> Fixes: ce757f5c9a ("ethdev: new method to retrieve extended statistics")
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>

I'm unsure on how verbose commit messages are ideal,
but there's certainly enough description here :)

Acked-by: Harry van Haaren <harry.van.haaren at intel.com>