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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alexey Kodanev <alexey.kodanev@oracle.com>,
        Neil Horman <nhorman@tuxdriver.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.4 28/36] sctp: fix dst refcnt leak in sctp_v6_get_dst()
Date:   Fri,  9 Mar 2018 16:18:44 -0800
Message-Id: <20180310001808.915272334@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexey Kodanev <alexey.kodanev@oracle.com>


[ Upstream commit 957d761cf91cdbb175ad7d8f5472336a4d54dbf2 ]

When going through the bind address list in sctp_v6_get_dst() and
the previously found address is better ('matchlen > bmatchlen'),
the code continues to the next iteration without releasing currently
held destination.

Fix it by releasing 'bdst' before continue to the next iteration, and
instead of introducing one more '!IS_ERR(bdst)' check for dst_release(),
move the already existed one right after ip6_dst_lookup_flow(), i.e. we
shouldn't proceed further if we get an error for the route lookup.

Fixes: dbc2b5e9a09e ("sctp: fix src address selection if using secondary addresses for ipv6")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sctp/ipv6.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -323,8 +323,10 @@ static void sctp_v6_get_dst(struct sctp_
 		final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
 		bdst = ip6_dst_lookup_flow(sk, fl6, final_p);
 
-		if (!IS_ERR(bdst) &&
-		    ipv6_chk_addr(dev_net(bdst->dev),
+		if (IS_ERR(bdst))
+			continue;
+
+		if (ipv6_chk_addr(dev_net(bdst->dev),
 				  &laddr->a.v6.sin6_addr, bdst->dev, 1)) {
 			if (!IS_ERR_OR_NULL(dst))
 				dst_release(dst);
@@ -333,8 +335,10 @@ static void sctp_v6_get_dst(struct sctp_
 		}
 
 		bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
-		if (matchlen > bmatchlen)
+		if (matchlen > bmatchlen) {
+			dst_release(bdst);
 			continue;
+		}
 
 		if (!IS_ERR_OR_NULL(dst))
 			dst_release(dst);