On Fri, Sep 22, 2017 at 6:41 AM, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> Currently if the stat type is invalid then data[i] is being set
> either by dereferencing a null pointer p, or it is reading from
> an incorrect previous location if we had a valid stat type
> previously. Fix this by nullify pointer p if a stat type is
> invalid and only setting data if p is not null.
>
> Detected by CoverityScan, CID#113385 ("Explicit null dereferenced")
>
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
> drivers/net/ethernet/intel/e1000/e1000_ethtool.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> index ec8aa4562cc9..724c93a6ea92 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_ethtool.c
> @@ -1824,7 +1824,7 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
> {
> struct e1000_adapter *adapter = netdev_priv(netdev);
> int i;
> - char *p = NULL;
> + char *p;
> const struct e1000_stats *stat = e1000_gstrings_stats;
>
> e1000_update_stats(adapter);
I was honestly happier with the portion of the first patch that moved
this into the loop.
> @@ -1837,16 +1837,18 @@ static void e1000_get_ethtool_stats(struct net_device *netdev,
> p = (char *)adapter + stat->stat_offset;
> break;
> default:
> + p = NULL;
> WARN_ONCE(1, "Invalid E1000 stat type: %u index %d\n",
> stat->type, i);
> break;
> }
>
> - if (stat->sizeof_stat == sizeof(u64))
> - data[i] = *(u64 *)p;
> - else
> - data[i] = *(u32 *)p;
> -
> + if (p) {
> + if (stat->sizeof_stat == sizeof(u64))
> + data[i] = *(u64 *)p;
> + else
> + data[i] = *(u32 *)p;
> + }
> stat++;
> }
Instead of doing all this why not just call out a "continue;" instead
of a "break" if the type isn't recognized, and move the stat++ into
the loop declaration and process it at the same time as i++? That
would clean most of this up and we don't have to worry about any loop
carried variables and the like.
> /* BUG_ON(i != E1000_STATS_LEN); */
> --
> 2.14.1
>
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