From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Maloy Subject: [net 1/1] tipc: Unclone message at secondary destination lookup Date: Sat, 7 Oct 2017 15:07:20 +0200 Message-ID: <1507381640-29340-1-git-send-email-jon.maloy@ericsson.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , To: , Return-path: Received: from sesbmg22.ericsson.net ([193.180.251.48]:51854 "EHLO sesbmg22.ericsson.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751119AbdJGNHf (ORCPT ); Sat, 7 Oct 2017 09:07:35 -0400 Sender: netdev-owner@vger.kernel.org List-ID: When a bundling message is received, the function tipc_link_input() calls function tipc_msg_extract() to unbundle all inner messages of the bundling message before adding them to input queue. The function tipc_msg_extract() just clones all inner skb for all inner messagges from the bundling skb. This means that the skb headroom of an inner message overlaps with the data part of the preceding message in the bundle. If the message in question is a name addressed message, it may be subject to a secondary destination lookup, and eventually be sent out on one of the interfaces again. But, since what is perceived as headroom by the device driver in reality is the last bytes of the preceding message in the bundle, the latter will be overwritten by the MAC addresses of the L2 header. If the preceding message has not yet been consumed by the user, it will evenually be delivered with corrupted contents. This commit fixes this by uncloning all messages passing through the function tipc_msg_lookup_dest(), hence ensuring that the headroom is always valid when the message is passed on. Signed-off-by: Tung Nguyen Signed-off-by: Jon Maloy --- net/tipc/msg.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/tipc/msg.c b/net/tipc/msg.c index 121e59a..17146c1 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -568,6 +568,14 @@ bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err) msg_set_destnode(msg, dnode); msg_set_destport(msg, dport); *err = TIPC_OK; + + if (!skb_cloned(skb)) + return true; + + /* Unclone buffer in case it was bundled */ + if (pskb_expand_head(skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC)) + return false; + return true; } -- 2.1.4