From patchwork Wed Nov 14 13:46:18 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Simon Wunderlich X-Patchwork-Id: 17620 X-Patchwork-Delegate: sw@simonwunderlich.de Return-Path: X-Original-To: patchwork@open-mesh.org Delivered-To: patchwork@open-mesh.org Received: from open-mesh.org (localhost [IPv6:::1]) by open-mesh.org (Postfix) with ESMTP id 6993B828CF; Wed, 14 Nov 2018 14:46:30 +0100 (CET) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=79.140.42.25; helo=mail.mail.packetmixer.de; envelope-from=sw@simonwunderlich.de; receiver= Received: from mail.mail.packetmixer.de (packetmixer.de [79.140.42.25]) by open-mesh.org (Postfix) with ESMTPS id D41B6827C7 for ; Wed, 14 Nov 2018 14:46:26 +0100 (CET) Received: from kero.packetmixer.de (unknown [IPv6:2001:16b8:5504:3000:2117:4962:5a5:5afe]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mail.packetmixer.de (Postfix) with ESMTPSA id 5695B6204E; Wed, 14 Nov 2018 14:46:26 +0100 (CET) From: Simon Wunderlich To: davem@davemloft.net Date: Wed, 14 Nov 2018 14:46:18 +0100 Message-Id: <20181114134618.17557-3-sw@simonwunderlich.de> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20181114134618.17557-1-sw@simonwunderlich.de> References: <20181114134618.17557-1-sw@simonwunderlich.de> MIME-Version: 1.0 Subject: [B.A.T.M.A.N.] [PATCH 2/2] batman-adv: Expand merged fragment buffer for full packet X-BeenThere: b.a.t.m.a.n@lists.open-mesh.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: The list for a Better Approach To Mobile Ad-hoc Networking List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: The list for a Better Approach To Mobile Ad-hoc Networking Cc: netdev@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org Errors-To: b.a.t.m.a.n-bounces@lists.open-mesh.org Sender: "B.A.T.M.A.N" From: Sven Eckelmann The complete size ("total_size") of the fragmented packet is stored in the fragment header and in the size of the fragment chain. When the fragments are ready for merge, the skbuff's tail of the first fragment is expanded to have enough room after the data pointer for at least total_size. This means that it gets expanded by total_size - first_skb->len. But this is ignoring the fact that after expanding the buffer, the fragment header is pulled by from this buffer. Assuming that the tailroom of the buffer was already 0, the buffer after the data pointer of the skbuff is now only total_size - len(fragment_header) large. When the merge function is then processing the remaining fragments, the code to copy the data over to the merged skbuff will cause an skb_over_panic when it tries to actually put enough data to fill the total_size bytes of the packet. The size of the skb_pull must therefore also be taken into account when the buffer's tailroom is expanded. Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Reported-by: Martin Weinelt Co-authored-by: Linus Lüssing Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/fragmentation.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index 0fddc17106bd..5b71a289d04f 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -275,7 +275,7 @@ batadv_frag_merge_packets(struct hlist_head *chain) kfree(entry); packet = (struct batadv_frag_packet *)skb_out->data; - size = ntohs(packet->total_size); + size = ntohs(packet->total_size) + hdr_size; /* Make room for the rest of the fragments. */ if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) {