From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751896Ab3FWPg2 (ORCPT ); Sun, 23 Jun 2013 11:36:28 -0400 Received: from mail-la0-f50.google.com ([209.85.215.50]:59691 "EHLO mail-la0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148Ab3FWPgZ (ORCPT ); Sun, 23 Jun 2013 11:36:25 -0400 Message-ID: <51C715F5.2050300@cogentembedded.com> Date: Sun, 23 Jun 2013 19:36:21 +0400 From: Sergei Shtylyov User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: linux-kernel@vger.kernel.org, "David S. Miller" , Jason Wang , Eric Dumazet , Neil Horman , netdev@vger.kernel.org, Brad Hubbard Subject: Re: [PATCH net] tun: fix recovery from gup errors References: <20130623141903.GA21029@redhat.com> In-Reply-To: <20130623141903.GA21029@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello. On 23-06-2013 18:19, Michael S. Tsirkin wrote: > get user pages might fail partially in tun zero copy > mode. To recover we need to put all pages that we got, > but code used a wrong index resulting in double-free > errors. > Reported-by: Brad Hubbard > Signed-off-by: Michael S. Tsirkin > --- > I haven't figured out why do we get failures, > but recovery is clearly wrong. > This is also -stable material. > drivers/net/tun.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index bfa9bb4..c098b1e 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1010,8 +1010,9 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, > return -EMSGSIZE; > num_pages = get_user_pages_fast(base, size, 0, &page[i]); > if (num_pages != size) { > - for (i = 0; i < num_pages; i++) > - put_page(page[i]); > + int j; Empty line wouldn't hurt here, after declaration. > + for (j = 0; j < num_pages; j++) > + put_page(page[i + j]);