netdev - RE: [net-next] tipc: add NULL pointer check

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Date:   Wed, 3 Apr 2019 14:27:18 +0000
From:   Jon Maloy <jon.maloy@...csson.com>
To:     Bo YU <tsu.yubo@...il.com>
CC:     Hoang Huu Le <hoang.h.le@...tech.com.au>,
        "maloy@...jonn.com" <maloy@...jonn.com>,
        "ying.xue@...driver.com" <ying.xue@...driver.com>,
        "tipc-discussion@...ts.sourceforge.net" 
        <tipc-discussion@...ts.sourceforge.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [net-next] tipc: add NULL pointer check

> -----Original Message-----
> From: Bo YU <tsu.yubo@...il.com>
> Sent: 3-Apr-19 09:10
> To: Jon Maloy <jon.maloy@...csson.com>
> Cc: Hoang Huu Le <hoang.h.le@...tech.com.au>; maloy@...jonn.com;
> ying.xue@...driver.com; tipc-discussion@...ts.sourceforge.net;
> netdev@...r.kernel.org
> Subject: Re: [net-next] tipc: add NULL pointer check
> 
> On Wed, Apr 3, 2019 at 8:55 PM Jon Maloy <jon.maloy@...csson.com>
> wrote:
> >
> > Acked-by: Jon Maloy <jon.maloy@...csson.com>
> >
> > Although "somehow" is not the good term here,- the reason is obvious
> when looking into tipc_sk_proto_rcv().
> If so,skb_peek in tipc_mcast_xmit() maybe alert?

Don't understand your question. tipc_mcast_xmit() is on the send path,  we are on the receive path here.
Besides, this is a completely normal occurrence, so no need for any warning.

///jon
 
> >
> >
> > > -----Original Message-----
> > > From: netdev-owner@...r.kernel.org <netdev-
> owner@...r.kernel.org> On
> > > Behalf Of Hoang Le
> > > Sent: 3-Apr-19 02:05
> > > To: Jon Maloy <jon.maloy@...csson.com>; maloy@...jonn.com;
> > > ying.xue@...driver.com; tipc-discussion@...ts.sourceforge.net;
> > > netdev@...r.kernel.org
> > > Subject: [net-next] tipc: add NULL pointer check
> > >
> > > skb somehow dequeued out of inputq before processing, it causes to
> > > NULL pointer and kernel crashed.
> > >
> > > Add checking skb valid before using.
> > >
> > > Fixes: c55c8edafa9 ("tipc: smooth change between replicast and
> > > broadcast")
> > > Reported-by: Tuong Lien Tong <tuong.t.lien@...tech.com.au>
> > > Acked-by: Ying Xue <ying.xue@...driver.com>
> > > Signed-off-by: Hoang Le <hoang.h.le@...tech.com.au>
> > > ---
> > >  net/tipc/bcast.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c index
> > > 76e14dc08bb9..6c997d4a6218 100644
> > > --- a/net/tipc/bcast.c
> > > +++ b/net/tipc/bcast.c
> > > @@ -769,6 +769,9 @@ void tipc_mcast_filter_msg(struct net *net,
> > > struct sk_buff_head *defq,
> > >       u32 node, port;
> > >
> > >       skb = skb_peek(inputq);
> > > +     if (!skb)
> > > +             return;
> > > +
> > >       hdr = buf_msg(skb);
> > >
> > >       if (likely(!msg_is_syn(hdr) && skb_queue_empty(defq)))
> > > --
> > > 2.17.1
> >