From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760664Ab3GZVgO (ORCPT ); Fri, 26 Jul 2013 17:36:14 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50831 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759934Ab3GZUse (ORCPT ); Fri, 26 Jul 2013 16:48:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , "David S. Miller" Subject: [ 23/79] tuntap: correctly linearize skb when zerocopy is used Date: Fri, 26 Jul 2013 13:47:13 -0700 Message-Id: <20130726204724.377912151@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130726204721.849052763@linuxfoundation.org> References: <20130726204721.849052763@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang [ Upstream commit 3dd5c3308e8b671e8e8882ba972f51cefbe9fd0d ] Userspace may produce vectors greater than MAX_SKB_FRAGS. When we try to linearize parts of the skb to let the rest of iov to be fit in the frags, we need count copylen into linear when calling tun_alloc_skb() instead of partly counting it into data_len. Since this breaks zerocopy_sg_from_iovec() since its inner counter assumes nr_frags should be zero at beginning. This cause nr_frags to be increased wrongly without setting the correct frags. This bug were introduced from 0690899b4d4501b3505be069b9a687e68ccbe15b (tun: experimental zero copy tx support) Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1044,7 +1044,7 @@ static ssize_t tun_get_user(struct tun_s { struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) }; struct sk_buff *skb; - size_t len = total_len, align = NET_SKB_PAD; + size_t len = total_len, align = NET_SKB_PAD, linear; struct virtio_net_hdr gso = { 0 }; int offset = 0; int copylen; @@ -1108,10 +1108,13 @@ static ssize_t tun_get_user(struct tun_s copylen = gso.hdr_len; if (!copylen) copylen = GOODCOPY_LEN; - } else + linear = copylen; + } else { copylen = len; + linear = gso.hdr_len; + } - skb = tun_alloc_skb(tfile, align, copylen, gso.hdr_len, noblock); + skb = tun_alloc_skb(tfile, align, copylen, linear, noblock); if (IS_ERR(skb)) { if (PTR_ERR(skb) != -EAGAIN) tun->dev->stats.rx_dropped++;