[PATCH net-next v14 12/13] net: ethtool: strset: Allow querying phy stats by index

[Maxime Chevallier]

Hello Simon,

On Tue, 2 Jul 2024 11:54:11 +0100
Simon Horman <horms at kernel.org> wrote:

> On Mon, Jul 01, 2024 at 03:17:58PM +0200, Maxime Chevallier wrote:
> > The ETH_SS_PHY_STATS command gets PHY statistics. Use the phydev pointer
> > from the ethnl request to allow query phy stats from each PHY on the
> > link.
> > 
> > Signed-off-by: Maxime Chevallier <maxime.chevallier at bootlin.com>
> > ---
> >  net/ethtool/strset.c | 24 +++++++++++++++++-------
> >  1 file changed, 17 insertions(+), 7 deletions(-)
> > 
> > diff --git a/net/ethtool/strset.c b/net/ethtool/strset.c  
> 
> ...
> 
> > @@ -279,6 +280,8 @@ static int strset_prepare_data(const struct ethnl_req_info *req_base,
> >  	const struct strset_req_info *req_info = STRSET_REQINFO(req_base);
> >  	struct strset_reply_data *data = STRSET_REPDATA(reply_base);
> >  	struct net_device *dev = reply_base->dev;
> > +	struct nlattr **tb = info->attrs;  
> 
> Hi Maxime,
> 
> Elsewhere in this function it is assumed that info may be NULL.
> But here it is dereferenced unconditionally.

Hmm in almst all netlink commands we do dereference the genl_info *info
pointer without checks.

I've looked into net/netlink/genetlink.c to backtrack call-sites and it
looks to be that indeed info can't be NULL (either populated from
genl_start() or genl_family_rcv_msg_doit(). Maybe Jakub can confirm
this ?

If what I say above is correct, I can include a small patch to remove
the un-necessary check that makes smatch think the genl_info pointer can
be NULL.

Thanks for the report,

Maxime