Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934680AbcLIQVi (ORCPT ); Fri, 9 Dec 2016 11:21:38 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:55734 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933992AbcLIQVe (ORCPT ); Fri, 9 Dec 2016 11:21:34 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Amir Vadai , "David S. Miller" Subject: [PATCH 4.8 16/45] net/sched: pedit: make sure that offset is valid Date: Fri, 9 Dec 2016 17:20:45 +0100 Message-Id: <20161209161755.578560208@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161209161754.912203877@linuxfoundation.org> References: <20161209161754.912203877@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1849 Lines: 68 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amir Vadai [ Upstream commit 95c2027bfeda21a28eb245121e6a249f38d0788e ] Add a validation function to make sure offset is valid: 1. Not below skb head (could happen when offset is negative). 2. Validate both 'offset' and 'at'. Signed-off-by: Amir Vadai Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/act_pedit.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) --- a/net/sched/act_pedit.c +++ b/net/sched/act_pedit.c @@ -108,6 +108,17 @@ static void tcf_pedit_cleanup(struct tc_ kfree(keys); } +static bool offset_valid(struct sk_buff *skb, int offset) +{ + if (offset > 0 && offset > skb->len) + return false; + + if (offset < 0 && -offset > skb_headroom(skb)) + return false; + + return true; +} + static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a, struct tcf_result *res) { @@ -134,6 +145,11 @@ static int tcf_pedit(struct sk_buff *skb if (tkey->offmask) { char *d, _d; + if (!offset_valid(skb, off + tkey->at)) { + pr_info("tc filter pedit 'at' offset %d out of bounds\n", + off + tkey->at); + goto bad; + } d = skb_header_pointer(skb, off + tkey->at, 1, &_d); if (!d) @@ -146,10 +162,10 @@ static int tcf_pedit(struct sk_buff *skb " offset must be on 32 bit boundaries\n"); goto bad; } - if (offset > 0 && offset > skb->len) { - pr_info("tc filter pedit" - " offset %d can't exceed pkt length %d\n", - offset, skb->len); + + if (!offset_valid(skb, off + offset)) { + pr_info("tc filter pedit offset %d out of bounds\n", + offset); goto bad; }