Patch "inet: fix possible request socket leak" has been added to the 4.1-stable tree

[<gregkh@linuxfoundation.org>]

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

    inet: fix possible request socket leak

to the 4.1-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:
     inet-fix-possible-request-socket-leak.patch
and it can be found in the queue-4.1 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 Sat Sep 26 11:13:07 PDT 2015
From: Eric Dumazet <edumazet@google.com>
Date: Mon, 10 Aug 2015 15:07:34 -0700
Subject: inet: fix possible request socket leak

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 3257d8b12f954c462d29de6201664a846328a522 ]

In commit b357a364c57c9 ("inet: fix possible panic in
reqsk_queue_unlink()"), I missed fact that tcp_check_req()
can return the listener socket in one case, and that we must
release the request socket refcount or we leak it.

Tested:

 Following packetdrill test template shows the issue

0     socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0    setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0    bind(3, ..., ...) = 0
+0    listen(3, 1) = 0

+0    < S 0:0(0) win 2920 <mss 1460,sackOK,nop,nop>
+0    > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
+.002 < . 1:1(0) ack 21 win 2920
+0    > R 21:21(0)

Fixes: b357a364c57c9 ("inet: fix possible panic in reqsk_queue_unlink()")
Signed-off-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/ipv4/tcp_ipv4.c |    2 +-
 net/ipv6/tcp_ipv6.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1348,7 +1348,7 @@ static struct sock *tcp_v4_hnd_req(struc
 	req = inet_csk_search_req(sk, th->source, iph->saddr, iph->daddr);
 	if (req) {
 		nsk = tcp_check_req(sk, skb, req, false);
-		if (!nsk)
+		if (!nsk || nsk == sk)
 			reqsk_put(req);
 		return nsk;
 	}
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -946,7 +946,7 @@ static struct sock *tcp_v6_hnd_req(struc
 				   &ipv6_hdr(skb)->daddr, tcp_v6_iif(skb));
 	if (req) {
 		nsk = tcp_check_req(sk, skb, req, false);
-		if (!nsk)
+		if (!nsk || nsk == sk)
 			reqsk_put(req);
 		return nsk;
 	}


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

queue-4.1/udp-fix-dst-races-with-multicast-early-demux.patch
queue-4.1/fq_codel-fix-a-use-after-free.patch
queue-4.1/inet-fix-possible-request-socket-leak.patch
queue-4.1/ipv6-lock-socket-in-ip6_datagram_connect.patch
queue-4.1/net-fix-skb-csum-races-when-peeking.patch
queue-4.1/inet-fix-races-with-reqsk-timers.patch
queue-4.1/net-graceful-exit-from-netif_alloc_netdev_queues.patch
queue-4.1/bridge-fix-potential-crash-in-__netdev_pick_tx.patch
queue-4.1/inet-frags-fix-defragmented-packet-s-ip-header-for-af_packet.patch