From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: tun issue after e0b46d0ee9c: tun: Use iovec iterators Date: Mon, 01 Dec 2014 05:41:00 +0008 Message-ID: <1417411980.7521.0@smtp.corp.redhat.com> References: <5478CC27.9040705@redhat.com> <20141128235935.GA2178@gondor.apana.org.au> <20141130100331.GA10050@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Cc: Marcelo Ricardo Leitner , netdev To: Herbert Xu Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55379 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751627AbaLAFdI (ORCPT ); Mon, 1 Dec 2014 00:33:08 -0500 In-Reply-To: <20141130100331.GA10050@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, Nov 30, 2014 at 6:03 PM, Herbert Xu wrote: > On Sat, Nov 29, 2014 at 07:59:35AM +0800, Herbert Xu wrote: >> On Fri, Nov 28, 2014 at 05:25:27PM -0200, Marcelo Ricardo Leitner >> wrote: >> > >> > I saw there are tun updates on Dave's queue but none seemed to >> handle this. >> > >> > I can't use current net-next >> > (799d2fff1858004526ad75d66a5dd8a5cce6ad40) on a kvm hypervisor >> > because tun got clogged somehow. Bisected down to: >> > >> > commit e0b46d0ee9c240c7430a47e9b0365674d4a04522 >> > Author: Herbert Xu >> > Date: Fri Nov 7 21:22:23 2014 +0800 >> >> Does this patch help? > > Oops, there was an embarrassing typo in the patch which causes > it to not even build. Here is the corrected version. > > -- >8 -- > Subject: tun: Fix GSO meta-data handling in tun_get_user > > When we write the GSO meta-data in tun_get_user we end up advancing > the IO vector twice, thus exhausting the user buffer before we can > finish writing the packet. > > Fixes: f5ff53b4d97c ("{macvtap,tun}_get_user(): switch to iov_iter") > Reported-by: Marcelo Ricardo Leitner > Signed-off-by: Herbert Xu > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 4b743c6..6d44da1 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1052,7 +1052,7 @@ static ssize_t tun_get_user(struct tun_struct > *tun, struct tun_file *tfile, > > if (gso.hdr_len > len) > return -EINVAL; > - iov_iter_advance(from, tun->vnet_hdr_sz); > + iov_iter_advance(from, tun->vnet_hdr_sz - sizeof(gso)); > } > > if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) { > Acked-by: Jason Wang