From patchwork Sat Oct 18 09:26:04 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li RongQing X-Patchwork-Id: 400661 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 652611400A6 for ; Sat, 18 Oct 2014 20:26:16 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750996AbaJRJ0N (ORCPT ); Sat, 18 Oct 2014 05:26:13 -0400 Received: from mail-pa0-f44.google.com ([209.85.220.44]:56010 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbaJRJ0L (ORCPT ); Sat, 18 Oct 2014 05:26:11 -0400 Received: by mail-pa0-f44.google.com with SMTP id et14so2226035pad.17 for ; Sat, 18 Oct 2014 02:26:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=96VYCjo9YPsB0cOzo5Iro3G0wVdF93ES2n2p6kjceXQ=; b=Ovrf3chYjUp4hBz+ibESdY34JZYQztPDPIU0eGlcMwTbXz9TuAewvZIiJOms43HqPA UgpcAJQt2Rb9LRC75VPbgauPvsCCHtfmxKdtrA2IEZ0PZs55bomPN5y0n3z8UZTFWMZl XJPUQn+R438eqdVCUd9q5A5fmVyvGpO/veHa1YbWznDbNvyTQeWJdUzZUlS7w+pjX14H N+QDWpk0Dj6OoHMyewbrmM9il7YRp3CAC+dv7M9nb3zFda6RaSvwbD536WAQo6u5A2Xz q1ariYtpT/ccGr3lVPSi+M1gmSCDap/FlGObzOaFdvIapfheU28E4PTHSZMJm1eFsi7e 97dQ== X-Received: by 10.70.128.40 with SMTP id nl8mr915462pdb.131.1413624370333; Sat, 18 Oct 2014 02:26:10 -0700 (PDT) Received: from localhost ([106.120.101.38]) by mx.google.com with ESMTPSA id xf9sm3690383pab.2.2014.10.18.02.26.08 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Sat, 18 Oct 2014 02:26:09 -0700 (PDT) From: roy.qing.li@gmail.com To: netdev@vger.kernel.org Cc: weichunc@plumgrid.com Subject: [PATCH] ipv4: fix a potential use after free in gre_offload.c Date: Sat, 18 Oct 2014 17:26:04 +0800 Message-Id: <1413624364-12944-1-git-send-email-roy.qing.li@gmail.com> X-Mailer: git-send-email 1.7.10.4 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Li RongQing pskb_may_pull() may change skb->data and make greh pointer oboslete; so need to reassign greh; but since first calling pskb_may_pull already ensured that skb->data has enough space for greh, so move the reference of greh before second calling pskb_may_pull(), to avoid reassign greh. Fixes: 7a7ffbabf9("ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC") Cc: Wei-Chun Chao Signed-off-by: Li RongQing Acked-by: Eric Dumazet --- net/ipv4/gre_offload.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c index a777295..ccda096 100644 --- a/net/ipv4/gre_offload.c +++ b/net/ipv4/gre_offload.c @@ -55,13 +55,13 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, if (csum) skb->encap_hdr_csum = 1; - if (unlikely(!pskb_may_pull(skb, ghl))) - goto out; - /* setup inner skb. */ skb->protocol = greh->protocol; skb->encapsulation = 0; + if (unlikely(!pskb_may_pull(skb, ghl))) + goto out; + __skb_pull(skb, ghl); skb_reset_mac_header(skb); skb_set_network_header(skb, skb_inner_network_offset(skb));