Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753798AbcKYIjj (ORCPT ); Fri, 25 Nov 2016 03:39:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:45259 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753312AbcKYIcm (ORCPT ); Fri, 25 Nov 2016 03:32:42 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Eric Dumazet , Hans Westgaard Ry , =?UTF-8?q?H=C3=A5kon=20Bugge?= , "David S . Miller" , Jiri Slaby Subject: [PATCH 3.12 101/127] tcp: fix potential memory corruption Date: Fri, 25 Nov 2016 09:30:14 +0100 Message-Id: X-Mailer: git-send-email 2.10.2 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 42 From: Eric Dumazet 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ Upstream commit ac9e70b17ecd7c6e933ff2eaf7ab37429e71bf4d ] Imagine initial value of max_skb_frags is 17, and last skb in write queue has 15 frags. Then max_skb_frags is lowered to 14 or smaller value. tcp_sendmsg() will then be allowed to add additional page frags and eventually go past MAX_SKB_FRAGS, overflowing struct skb_shared_info. Fixes: 5f74f82ea34c ("net:Add sysctl_max_skb_frags") Signed-off-by: Eric Dumazet Cc: Hans Westgaard Ry Cc: Håkon Bugge Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 392d3259f9ad..3e63b5fb2121 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1169,7 +1169,7 @@ new_segment: if (!skb_can_coalesce(skb, i, pfrag->page, pfrag->offset)) { - if (i == sysctl_max_skb_frags || !sg) { + if (i >= sysctl_max_skb_frags || !sg) { tcp_mark_push(tp, skb); goto new_segment; } -- 2.10.2