From patchwork Wed Dec 11 14:39:26 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 300107 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 20EAE2C0085 for ; Thu, 12 Dec 2013 01:39:59 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Vqkx7-0000wL-Cg; Wed, 11 Dec 2013 14:39:53 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Vqkwi-0000gP-1R for kernel-team@lists.ubuntu.com; Wed, 11 Dec 2013 14:39:28 +0000 Received: from bl15-242-146.dsl.telepac.pt ([188.80.242.146] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Vqkwh-0008PH-NW; Wed, 11 Dec 2013 14:39:27 +0000 From: Luis Henriques To: Jason Wang Subject: [3.11.y.z extended stable] Patch "tuntap: limit head length of skb allocated" has been added to staging queue Date: Wed, 11 Dec 2013 14:39:26 +0000 Message-Id: <1386772766-7840-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 X-Extended-Stable: 3.11 Cc: kernel-team@lists.ubuntu.com, "David S. Miller" , Stefan Hajnoczi , "Michael S. Tsirkin" X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled tuntap: limit head length of skb allocated to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 7a7ba532fe257bd45ffa545d47d4cb79b9059f0a Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 13 Nov 2013 14:00:39 +0800 Subject: tuntap: limit head length of skb allocated commit 96f8d9ecf227638c89f98ccdcdd50b569891976c upstream. 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. Cc: Stefan Hajnoczi Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- drivers/net/tun.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) -- 1.8.3.2 diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 68b9aa3..171a88f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1067,6 +1067,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, struct sk_buff *skb; size_t len = total_len, align = NET_SKB_PAD, linear; struct virtio_net_hdr gso = { 0 }; + int good_linear; int offset = 0; int copylen; bool zerocopy = false; @@ -1107,12 +1108,16 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, return -EINVAL; } + good_linear = SKB_MAX_HEAD(align); + if (msg_control) { /* There are 256 bytes to be copied in skb, so there is * enough room for skb expand head in case it is used. * The rest of the buffer is mapped from userspace. */ copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN; + if (copylen > good_linear) + copylen = good_linear; linear = copylen; if (iov_pages(iv, offset + copylen, count) <= MAX_SKB_FRAGS) zerocopy = true; @@ -1120,7 +1125,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, if (!zerocopy) { copylen = len; - linear = gso.hdr_len; + if (gso.hdr_len > good_linear) + linear = good_linear; + else + linear = gso.hdr_len; } skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);