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

[Jon M. <jon...@er...>]

> -----Original Message-----
> From: Bo YU <tsu...@gm...>
> Sent: 3-Apr-19 09:10
> To: Jon Maloy <jon...@er...>
> Cc: Hoang Huu Le <hoa...@de...>; ma...@do...;
> yin...@wi...; tip...@li...;
> ne...@vg...
> Subject: Re: [net-next] tipc: add NULL pointer check
> 
> On Wed, Apr 3, 2019 at 8:55 PM Jon Maloy <jon...@er...>
> wrote:
> >
> > Acked-by: Jon Maloy <jon...@er...>
> >
> > 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: net...@vg... <netdev-
> ow...@vg...> On
> > > Behalf Of Hoang Le
> > > Sent: 3-Apr-19 02:05
> > > To: Jon Maloy <jon...@er...>; ma...@do...;
> > > yin...@wi...; tip...@li...;
> > > ne...@vg...
> > > 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 <tuo...@de...>
> > > Acked-by: Ying Xue <yin...@wi...>
> > > Signed-off-by: Hoang Le <hoa...@de...>
> > > ---
> > >  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
> >