From patchwork Tue Apr 25 14:08:05 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 754844 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 3wC4pC5Hnvz9s8W for ; Wed, 26 Apr 2017 00:09:23 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=zx2c4.com header.i=@zx2c4.com header.b="kDiuErZD"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1431421AbdDYOI0 (ORCPT ); Tue, 25 Apr 2017 10:08:26 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:53685 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1431322AbdDYOIX (ORCPT ); Tue, 25 Apr 2017 10:08:23 -0400 Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 349e5af9; Tue, 25 Apr 2017 13:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=from:to:cc :subject:date:message-id; s=mail; bh=s6GkZ6gZKKx9JKButMNLHLu74lY =; b=kDiuErZDjDAtEAIPaOgml7LAeskmlpfQAX4Byaln4moi+Yl5xvn80lyU59g HO5KlTN2nkVjqx46Ko6P97ERXcomxoIP8Kz2FLZZzaK/a/vlbp0KZtt6PICTfq2Q cOG1B2kxa4kKxKVZAxE0NjlAZvT1uC4ua2Klxm5OjurYUzMpXYnr9PSQCQsR2Tbb S+f8/Un6oYJ+lmq6IsgjZ0qgMjH6sxcqTleDjGz9EDqKoJFJT8jT+QZxY2PdQaW1 sBPIhPmjlFR8zKHKguoC/Ax9C5eCRnHB/p3tG5D7WJr2SxCCTGw7E2gKM6qIEzKU pR2RX7tG92xl9FWcnxl8W/49oSw== Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 93c9e799 (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256:NO); Tue, 25 Apr 2017 13:59:41 +0000 (UTC) From: "Jason A. Donenfeld" To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net, David.Laight@aculab.com, kernel-hardening@lists.openwall.com Cc: "Jason A. Donenfeld" Subject: [PATCH 1/5] skbuff: return -EMSGSIZE in skb_to_sgvec to prevent overflow Date: Tue, 25 Apr 2017 16:08:05 +0200 Message-Id: <20170425140809.23881-1-Jason@zx2c4.com> X-Mailer: git-send-email 2.12.2 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This is a defense-in-depth measure in response to bugs like 4d6fa57b4dab0d77f4d8e9d9c73d1e63f6fe8fee. Signed-off-by: Jason A. Donenfeld --- net/core/skbuff.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f86bf69cfb8d..3c2a7f323722 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3489,7 +3489,9 @@ void __init skb_init(void) * @len: Length of buffer space to be mapped * * Fill the specified scatter-gather list with mappings/pointers into a - * region of the buffer space attached to a socket buffer. + * region of the buffer space attached to a socket buffer. Returns either + * the number of scatterlist items used, or -EMSGSIZE if the contents + * could not fit. */ static int __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) @@ -3512,6 +3514,9 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; + if (elt && sg_is_last(&sg[elt - 1])) + return -EMSGSIZE; + WARN_ON(start > offset + len); end = start + skb_frag_size(&skb_shinfo(skb)->frags[i]); @@ -3535,6 +3540,9 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) WARN_ON(start > offset + len); + if (elt && sg_is_last(&sg[elt - 1])) + return -EMSGSIZE; + end = start + frag_iter->len; if ((copy = end - offset) > 0) { if (copy > len)