From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757669AbbAYT10 (ORCPT ); Sun, 25 Jan 2015 14:27:26 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:57362 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754714AbbAYSI6 (ORCPT ); Sun, 25 Jan 2015 13:08:58 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Eckelmann , "David S. Miller" Subject: [PATCH 3.14 07/98] batman-adv: Unify fragment size calculation Date: Sun, 25 Jan 2015 10:06:25 -0800 Message-Id: <20150125180713.173995219@linuxfoundation.org> X-Mailer: git-send-email 2.2.2 In-Reply-To: <20150125180712.859646324@linuxfoundation.org> References: <20150125180712.859646324@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann [ Upstream commit 0402e444cd199389b7fe47be68a67b817e09e097 ] The fragmentation code was replaced in 610bfc6bc99bc83680d190ebc69359a05fc7f605 ("batman-adv: Receive fragmented packets and merge") by an implementation which can handle up to 16 fragments of a packet. The packet is prepared for the split in fragments by the function batadv_frag_send_packet and the actual split is done by batadv_frag_create. Both functions calculate the size of a fragment themself. But their calculation differs because batadv_frag_send_packet also subtracts ETH_HLEN. Therefore, the check in batadv_frag_send_packet "can a full fragment can be created?" may return true even when batadv_frag_create cannot create a full fragment. The function batadv_frag_create doesn't check the size of the skb before splitting it and therefore might try to create a larger fragment than the remaining buffer. This creates an integer underflow and an invalid len is given to skb_split. Signed-off-by: Sven Eckelmann Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/fragmentation.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -434,7 +434,7 @@ bool batadv_frag_send_packet(struct sk_b * fragments larger than BATADV_FRAG_MAX_FRAG_SIZE */ mtu = min_t(unsigned, mtu, BATADV_FRAG_MAX_FRAG_SIZE); - max_fragment_size = (mtu - header_size - ETH_HLEN); + max_fragment_size = mtu - header_size; max_packet_size = max_fragment_size * BATADV_FRAG_MAX_FRAGMENTS; /* Don't even try to fragment, if we need more than 16 fragments */