From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161475Ab3LFWSR (ORCPT ); Fri, 6 Dec 2013 17:18:17 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60847 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758778Ab3LFVx3 (ORCPT ); Fri, 6 Dec 2013 16:53:29 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jason Wang , Stefan Hajnoczi , "Michael S. Tsirkin" , "David S. Miller" Subject: [PATCH 3.10 11/58] macvtap: limit head length of skb allocated Date: Fri, 6 Dec 2013 13:51:42 -0800 Message-Id: <20131206214845.966583939@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.1.67.gb00d244 In-Reply-To: <20131206214844.906193530@linuxfoundation.org> References: <20131206214844.906193530@linuxfoundation.org> User-Agent: quilt/0.60-8.1.3 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 16a3fa28630331e28208872fa5341ce210b901c7 ] We currently use hdr_len as a hint of head length which is advertised by guest. But when guest advertise a very big value, it can lead to an 64K+ allocating of kmalloc() which has a very high possibility of failure when host memory is fragmented or under heavy stress. The huge hdr_len also reduce the effect of zerocopy or even disable if a gso skb is linearized in guest. To solves those issues, this patch introduces an upper limit (PAGE_SIZE) of the head, which guarantees an order 0 allocation each time. Signed-off-by: Jason Wang Cc: Stefan Hajnoczi Cc: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/macvtap.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -661,6 +661,7 @@ static ssize_t macvtap_get_user(struct m const struct iovec *iv, unsigned long total_len, size_t count, int noblock) { + int good_linear = SKB_MAX_HEAD(NET_IP_ALIGN); struct sk_buff *skb; struct macvlan_dev *vlan; unsigned long len = total_len; @@ -703,6 +704,8 @@ static ssize_t macvtap_get_user(struct m if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { copylen = vnet_hdr.hdr_len ? vnet_hdr.hdr_len : GOODCOPY_LEN; + if (copylen > good_linear) + copylen = good_linear; linear = copylen; if (iov_pages(iv, vnet_hdr_len + copylen, count) <= MAX_SKB_FRAGS) @@ -711,7 +714,10 @@ static ssize_t macvtap_get_user(struct m if (!zerocopy) { copylen = len; - linear = vnet_hdr.hdr_len; + if (vnet_hdr.hdr_len > good_linear) + linear = good_linear; + else + linear = vnet_hdr.hdr_len; } skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen,