Re: [net-next] tipc: add NULL pointer check

[Bo YU <tsu.yubo@gmail.com>]

On Wed, Apr 3, 2019 at 10:27 PM Jon Maloy <jon.maloy@ericsson.com> wrote:
>
> > -----Original Message-----
> > From: Bo YU <tsu.yubo@gmail.com>
> > Sent: 3-Apr-19 09:10
> > To: Jon Maloy <jon.maloy@ericsson.com>
> > Cc: Hoang Huu Le <hoang.h.le@dektech.com.au>; maloy@donjonn.com;
> > ying.xue@windriver.com; tipc-discussion@lists.sourceforge.net;
> > netdev@vger.kernel.org
> > Subject: Re: [net-next] tipc: add NULL pointer check
> >
> > On Wed, Apr 3, 2019 at 8:55 PM Jon Maloy <jon.maloy@ericsson.com>
> > wrote:
> > >
> > > Acked-by: Jon Maloy <jon.maloy@ericsson.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.
Ok, thank you for explation.
>
> ///jon
>
> > >
> > >
> > > > -----Original Message-----
> > > > From: netdev-owner@vger.kernel.org <netdev-
> > owner@vger.kernel.org> On
> > > > Behalf Of Hoang Le
> > > > Sent: 3-Apr-19 02:05
> > > > To: Jon Maloy <jon.maloy@ericsson.com>; maloy@donjonn.com;
> > > > ying.xue@windriver.com; tipc-discussion@lists.sourceforge.net;
> > > > netdev@vger.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@dektech.com.au>
> > > > Acked-by: Ying Xue <ying.xue@windriver.com>
> > > > Signed-off-by: Hoang Le <hoang.h.le@dektech.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
> > >