From a9e2971b8cd3ef469de0112ba15778b5b98ad72e Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Sat, 7 Oct 2017 15:07:20 +0200 Subject: tipc: Unclone message at secondary destination lookup 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 Signed-off-by: David S. Miller --- net/tipc/msg.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'net/tipc/msg.c') diff --git a/net/tipc/msg.c b/net/tipc/msg.c index 121e59a1d0e7..17146c16ee2d 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; } -- cgit