Patch "dccp: fix freeing skb too early for IPV6_RECVPKTINFO" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    dccp: fix freeing skb too early for IPV6_RECVPKTINFO

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dccp-fix-freeing-skb-too-early-for-ipv6_recvpktinfo.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Feb 23 21:13:19 CET 2017
From: Andrey Konovalov <andreyknvl@google.com>
Date: Thu, 16 Feb 2017 17:22:46 +0100
Subject: dccp: fix freeing skb too early for IPV6_RECVPKTINFO

From: Andrey Konovalov <andreyknvl@google.com>


[ Upstream commit 5edabca9d4cff7f1f2b68f0bac55ef99d9798ba4 ]

In the current DCCP implementation an skb for a DCCP_PKT_REQUEST packet
is forcibly freed via __kfree_skb in dccp_rcv_state_process if
dccp_v6_conn_request successfully returns.

However, if IPV6_RECVPKTINFO is set on a socket, the address of the skb
is saved to ireq->pktopts and the ref count for skb is incremented in
dccp_v6_conn_request, so skb is still in use. Nevertheless, it gets freed
in dccp_rcv_state_process.

Fix by calling consume_skb instead of doing goto discard and therefore
calling __kfree_skb.

Similar fixes for TCP:

fb7e2399ec17f1004c0e0ccfd17439f8759ede01 [TCP]: skb is unexpectedly freed.
0aea76d35c9651d55bbaf746e7914e5f9ae5a25d tcp: SYN packets are now
simply consumed

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/dccp/input.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -606,7 +606,8 @@ int dccp_rcv_state_process(struct sock *
 			if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
 								    skb) < 0)
 				return 1;
-			goto discard;
+			consume_skb(skb);
+			return 0;
 		}
 		if (dh->dccph_type == DCCP_PKT_RESET)
 			goto discard;


Patches currently in stable-queue which might be from andreyknvl@google.com are

queue-4.4/dccp-fix-freeing-skb-too-early-for-ipv6_recvpktinfo.patch
queue-4.4/ip-fix-ip_checksum-handling.patch
queue-4.4/net-llc-avoid-bug_on-in-skb_orphan.patch