From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752191Ab2JEG5J (ORCPT ); Fri, 5 Oct 2012 02:57:09 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:55777 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751481Ab2JEG5D (ORCPT ); Fri, 5 Oct 2012 02:57:03 -0400 Subject: Re: [PATCH] net: Fix skb_under_panic oops in neigh_resolve_output From: Eric Dumazet To: ramesh.nagappa@gmail.com Cc: bnramesh@yahoo.com, davem@davemloft.net, edumazet@google.com, ebiederm@xmission.com, xemul@parallels.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ramesh Nagappa In-Reply-To: <1349406325-3157-1-git-send-email-ramesh.nagappa@gmail.com> References: <1349406325-3157-1-git-send-email-ramesh.nagappa@gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 05 Oct 2012 08:27:25 +0200 Message-ID: <1349418445.21172.11.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-10-04 at 20:05 -0700, ramesh.nagappa@gmail.com wrote: > From: Ramesh Nagappa > > The retry loop in neigh_resolve_output() and neigh_connected_output() > call dev_hard_header() with out reseting the skb to network_header. > This causes the retry to fail with skb_under_panic. The fix is to > reset the network_header within the retry loop. > > Signed-off-by: Ramesh Nagappa > Reviewed-by: Shawn Lu > Reviewed-by: Robert Coulson > Reviewed-by: Billie Alsup > --- > net/core/neighbour.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/core/neighbour.c b/net/core/neighbour.c > index 117afaf..f50c542 100644 > --- a/net/core/neighbour.c > +++ b/net/core/neighbour.c > @@ -1313,6 +1313,7 @@ int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb) > > do { > seq = read_seqbegin(&neigh->ha_lock); > + __skb_pull(skb, skb_network_offset(skb)); This __skb_pull() could be done before the read_seqbegin() to keep the protected section short. > err = dev_hard_header(skb, dev, ntohs(skb->protocol), > neigh->ha, NULL, skb->len); > } while (read_seqretry(&neigh->ha_lock, seq)); > @@ -1342,10 +1343,9 @@ int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb) > unsigned int seq; > int err; > > - __skb_pull(skb, skb_network_offset(skb)); > - > do { > seq = read_seqbegin(&neigh->ha_lock); > + __skb_pull(skb, skb_network_offset(skb)); This __skb_pull() could be done before the read_seqbegin() to keep the protected section short. > err = dev_hard_header(skb, dev, ntohs(skb->protocol), > neigh->ha, NULL, skb->len); > } while (read_seqretry(&neigh->ha_lock, seq)); Thanks