Hi Wang cong,
After apply the patch, I did not hit the issue again.
Thank you~
Best Regards,
liujian
> -----Original Message-----
> From: Dingtianhong
> Sent: Monday, July 24, 2017 9:29 AM
> To: Cong Wang; liujian (CE)
> Cc: Willem de Bruijn; Dave Jones; alexander.le...@verizon.com;
> da...@davemloft.net; eduma...@google.com; will...@google.com;
> dan...@iogearbox.net; net...@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: af_packet: use after free in prb_retire_rx_blk_timer_expired
>
>
>
> On 2017/7/24 9:09, Ding Tianhong wrote:
> >
> >
> > On 2017/7/24 1:03, Cong Wang wrote:
> >> On Sun, Jul 23, 2017 at 5:48 AM, liujian (CE) <liujia...@huawei.com> wrote:
> >>> Hi
> >>>
> >>> I find it caused by below steps:
> >>> 1. set tp_version to TPACKET_V3 and req->tp_block_nr to 1 2. set
> >>> tp_block_nr to 0 Then pg_vec was freed, and we did not delete the
> >>> timer?
> >>
> >> Thanks for testing!
> >>
> >> Ah, I overlook the initialization case in my previous patch.
> >>
> >> How about the following one? Does it cover all the cases?
> >>
> >>
> >> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index
> >> 008bb34ee324..0615c2a950fa 100644
> >> --- a/net/packet/af_packet.c
> >> +++ b/net/packet/af_packet.c
> >> @@ -4329,7 +4329,7 @@ static int packet_set_ring(struct sock *sk,
> >> union tpacket_req_u *req_u,
> >> register_prot_hook(sk);
> >> }
> >> spin_unlock(&po->bind_lock);
> >> - if (closing && (po->tp_version > TPACKET_V2)) {
> >> + if (pg_vec && (po->tp_version > TPACKET_V2)) {
> >> /* Because we don't support block-based V3 on tx-ring
> */
> >> if (!tx_ring)
> >> prb_shutdown_retire_blk_timer(po,
> rb_queue);
> >>
> >> .
> >
> > Hi, Cong:
> >
> > It looks like could not cover the case: req->tp_block_nr = 2 ->
> reg->tp_block_nr = 1 .
> >
>
> Oh, looks like this case would never happen, so I think your solution is ok.
>
> > what about this way:
> > --- a/net/packet/af_packet.c
> > +++ b/net/packet/af_packet.c
> > @@ -4331,13 +4331,17 @@ static int packet_set_ring(struct sock *sk, union
> tpacket_req_u *req_u,
> > register_prot_hook(sk);
> > }
> > spin_unlock(&po->bind_lock);
> > - if (closing && (po->tp_version > TPACKET_V2)) {
> > + if ((closing || (pg_vec && !reg->tp_block_nr))&&
> > + (po->tp_version > TPACKET_V2)) {
> > /* Because we don't support block-based V3 on tx-ring */
> > if (!tx_ring)
> > prb_shutdown_retire_blk_timer(po,
> rb_queue);
> >
> >
>
> >>
> >
> >
> > .
> >
