Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752685AbcDZSSM (ORCPT ); Tue, 26 Apr 2016 14:18:12 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56240 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752501AbcDZSSH (ORCPT ); Tue, 26 Apr 2016 14:18:07 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Willem de Bruijn , "David S . Miller" , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 13/93] macvtap: always pass ethernet header in linear Date: Tue, 26 Apr 2016 11:16:13 -0700 Message-Id: <1461694653-29506-14-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1461694653-29506-1-git-send-email-kamal@canonical.com> References: <1461694653-29506-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2028 Lines: 57 4.2.8-ckt9 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Willem de Bruijn [ Upstream commit 8e2ad4113ce4671686740f808ff2795395c39eef ] The stack expects link layer headers in the skb linear section. Macvtap can create skbs with llheader in frags in edge cases: when (IFF_VNET_HDR is off or vnet_hdr.hdr_len < ETH_HLEN) and prepad + len > PAGE_SIZE and vnet_hdr.flags has no or bad csum. Add checks to ensure linear is always at least ETH_HLEN. At this point, len is already ensured to be >= ETH_HLEN. For backwards compatiblity, rounds up short vnet_hdr.hdr_len. This differs from tap and packet, which return an error. Fixes b9fb9ee07e67 ("macvtap: add GSO/csum offload support") Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Kamal Mostafa --- drivers/net/macvtap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 197c939..2311e1f 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -760,6 +760,8 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, macvtap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; if (copylen > good_linear) copylen = good_linear; + else if (copylen < ETH_HLEN) + copylen = ETH_HLEN; linear = copylen; i = *from; iov_iter_advance(&i, copylen); @@ -769,10 +771,11 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, if (!zerocopy) { copylen = len; - if (macvtap16_to_cpu(q, vnet_hdr.hdr_len) > good_linear) + linear = macvtap16_to_cpu(q, vnet_hdr.hdr_len); + if (linear > good_linear) linear = good_linear; - else - linear = macvtap16_to_cpu(q, vnet_hdr.hdr_len); + else if (linear < ETH_HLEN) + linear = ETH_HLEN; } skb = macvtap_alloc_skb(&q->sk, MACVTAP_RESERVE, copylen, -- 2.7.4