From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: Re: tun issue after e0b46d0ee9c: tun: Use iovec iterators Date: Sun, 30 Nov 2014 18:03:31 +0800 Message-ID: <20141130100331.GA10050@gondor.apana.org.au> References: <5478CC27.9040705@redhat.com> <20141128235935.GA2178@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev To: Marcelo Ricardo Leitner Return-path: Received: from helcar.apana.org.au ([209.40.204.226]:50208 "EHLO helcar.apana.org.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751142AbaK3KDe (ORCPT ); Sun, 30 Nov 2014 05:03:34 -0500 Content-Disposition: inline In-Reply-To: <20141128235935.GA2178@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: 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) { Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt