From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net 2/2] net: dev_queue_xmit_nit: fix potential NULL ptr dereference Date: Tue, 08 Jan 2013 11:22:23 -0800 Message-ID: <1357672943.18156.328.camel@edumazet-glaptop> References: <1357671093-9605-1-git-send-email-dborkman@redhat.com> <1357671093-9605-3-git-send-email-dborkman@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, Changli Gao To: Daniel Borkmann Return-path: Received: from mail-pb0-f48.google.com ([209.85.160.48]:37756 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753916Ab3AHTWZ (ORCPT ); Tue, 8 Jan 2013 14:22:25 -0500 Received: by mail-pb0-f48.google.com with SMTP id rq13so429757pbb.35 for ; Tue, 08 Jan 2013 11:22:25 -0800 (PST) In-Reply-To: <1357671093-9605-3-git-send-email-dborkman@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2013-01-08 at 19:51 +0100, Daniel Borkmann wrote: > Commit 71d9dec24dce548bf699815c976cf063ad9257e2 (``net: increase > skb->users instead of skb_clone()'') introduced a skb_clone in > dev_queue_xmit_nit that, when NULL, leaves the loop, but can still > be injected into pt_prev->func(). > > Cc: Changli Gao > Cc: Eric Dumazet > Signed-off-by: Daniel Borkmann > --- > net/core/dev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/core/dev.c b/net/core/dev.c > index 723dcd0..6c35c33 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -1827,7 +1827,7 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) > pt_prev = ptype; > } > } > - if (pt_prev) > + if (skb2 && pt_prev) > pt_prev->func(skb2, skb->dev, pt_prev, skb->dev); > rcu_read_unlock(); > } My opinion is this patch is not needed. pt_prev can be set only if skb2 is not NULL