netdev - Re: [PATCH net] sctp: remove sched init from sctp_stream

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Message-ID: <20190308170220.GE13515@localhost.localdomain>
Date:   Fri, 8 Mar 2019 14:02:20 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Neil Horman <nhorman@...driver.com>
Cc:     Xin Long <lucien.xin@...il.com>,
        network dev <netdev@...r.kernel.org>,
        linux-sctp@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH net] sctp: remove sched init from sctp_stream_init

On Fri, Mar 08, 2019 at 07:21:36AM -0500, Neil Horman wrote:
> On Fri, Mar 08, 2019 at 03:49:16PM +0800, Xin Long wrote:
> > syzbot reported a NULL-ptr deref caused by that sched->init() in
> > sctp_stream_init() set stream->rr_next = NULL.
> > 
> >   kasan: GPF could be caused by NULL-ptr deref or user memory access
> >   RIP: 0010:sctp_sched_rr_dequeue+0xd3/0x170 net/sctp/stream_sched_rr.c:141
> >   Call Trace:
> >     sctp_outq_dequeue_data net/sctp/outqueue.c:90 [inline]
> >     sctp_outq_flush_data net/sctp/outqueue.c:1079 [inline]
> >     sctp_outq_flush+0xba2/0x2790 net/sctp/outqueue.c:1205
> > 
> > All sched info is saved in sout->ext now, in sctp_stream_init()
> > sctp_stream_alloc_out() will not change it, there's no need to
> > call sched->init() again, since sctp_outq_init() has already
> > done it.

through sctp_sched_set_sched(), yes.  Thanks Xin.

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

> > 
> > Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
> > Reported-by: syzbot+4c9934f20522c0efd657@...kaller.appspotmail.com
> > Signed-off-by: Xin Long <lucien.xin@...il.com>
> > ---
> >  net/sctp/stream.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/net/sctp/stream.c b/net/sctp/stream.c
> > index 2936ed1..3b47457 100644
> > --- a/net/sctp/stream.c
> > +++ b/net/sctp/stream.c
> > @@ -230,8 +230,6 @@ int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
> >  	for (i = 0; i < stream->outcnt; i++)
> >  		SCTP_SO(stream, i)->state = SCTP_STREAM_OPEN;
> >  
> > -	sched->init(stream);
> > -
> >  in:
> >  	sctp_stream_interleave_init(stream);
> >  	if (!incnt)
> > -- 
> > 2.1.0
> > 
> > 
> Acked-by: Neil Horman <nhorman@...driver.com>
>