From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Abeni Subject: Re: [PATCH] IB/IPoIB: Check the headroom size Date: Wed, 26 Apr 2017 15:25:37 +0200 Message-ID: <1493213137.2152.2.camel@redhat.com> References: <1493114155-12101-1-git-send-email-honli@redhat.com> <1493134815.3041.72.camel@redhat.com> <1493192794.2409.3.camel@redhat.com> <20170426125230.GB19179@dhcp-13-42.nay.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Cc: Or Gerlitz , Doug Ledford , Erez Shitrit , Erez Shitrit , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Linux Netdev List , David Miller To: Honggang LI Return-path: In-Reply-To: <20170426125230.GB19179-Y5OA6DF/u0nid9cnFhDO8BcY2uh10dtjAL8bYrjMMd8@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On Wed, 2017-04-26 at 20:52 +0800, Honggang LI wrote: > On Wed, Apr 26, 2017 at 09:46:34AM +0200, Paolo Abeni wrote: > > On Wed, 2017-04-26 at 00:50 +0300, Or Gerlitz wrote: > > > so maybe @ least for the time being, we should be picking Hong's patch > > > with proper change log and without the giant stack dump till we have > > > something better. If you agree, can you do the re-write of the change > > > log? > > > > I think that Hong's patch is following the correct way to fix the > > issue: ipoib_hard_header() can't assume that the skb headroom is at > > least IPOIB_HARD_LEN bytes, as wrongly implied by commit fc791b633515 > > (my fault, I'm sorry). > > > > Perhaps we can make the code a little more robust with something > > alongside the following (only compile tested): > > --- > > diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c > > index d1d3fb7..d53d2e1 100644 > > --- a/drivers/infiniband/ulp/ipoib/ipoib_main.c > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c > > @@ -1160,6 +1160,11 @@ static int ipoib_hard_header(struct sk_buff *skb, > >                              const void *daddr, const void *saddr, unsigned len) > >  { > >         struct ipoib_header *header; > > +       int ret; > > + > > +       ret = skb_cow_head(skb, IPOIB_HARD_LEN); > > I don't think so. When this skb_under_panic arise, all slaves had been > removed from a busy bonding interface, so it is better to immediately > give up and return error. I fear we can hit the same condition even with other, more convoluted, setup (e.g. some kind of ip tunnel on top of ipoib) and the skb_cow_head() check should be cheap, in the common case. Anyway I'm fine even with the original fix, which has the advantage to minimize the side effects. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html