From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752559Ab3FXDXH (ORCPT ); Sun, 23 Jun 2013 23:23:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34179 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752417Ab3FXDXG (ORCPT ); Sun, 23 Jun 2013 23:23:06 -0400 Message-ID: <51C7BB8C.70304@redhat.com> Date: Mon, 24 Jun 2013 11:22:52 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: linux-kernel@vger.kernel.org, "David S. Miller" , 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 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2013 10:19 PM, 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. Acked-by: Jason Wang > 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; > + for (j = 0; j < num_pages; j++) > + put_page(page[i + j]); > return -EFAULT; > } > truesize = size * PAGE_SIZE;