linux-kernel - [PATCH 4.13 10/52] tcp: fix a request socket leak

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Date:   Mon, 18 Sep 2017 11:09:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.13 10/52] tcp: fix a request socket leak

4.13-stable review patch.  If anyone has any objections, please let me know.

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

From: Eric Dumazet <edumazet@...gle.com>


[ Upstream commit 1f3b359f1004bd34b7b0bad70b93e3c7af92a37b ]

While the cited commit fixed a possible deadlock, it added a leak
of the request socket, since reqsk_put() must be called if the BPF
filter decided the ACK packet must be dropped.

Fixes: d624d276d1dd ("tcp: fix possible deadlock in TCP stack vs BPF filter")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_ipv4.c |    6 +++---
 net/ipv6/tcp_ipv6.c |    6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1722,9 +1722,9 @@ process:
 		 */
 		sock_hold(sk);
 		refcounted = true;
-		if (tcp_filter(sk, skb))
-			goto discard_and_relse;
-		nsk = tcp_check_req(sk, skb, req, false);
+		nsk = NULL;
+		if (!tcp_filter(sk, skb))
+			nsk = tcp_check_req(sk, skb, req, false);
 		if (!nsk) {
 			reqsk_put(req);
 			goto discard_and_relse;
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1456,9 +1456,9 @@ process:
 		}
 		sock_hold(sk);
 		refcounted = true;
-		if (tcp_filter(sk, skb))
-			goto discard_and_relse;
-		nsk = tcp_check_req(sk, skb, req, false);
+		nsk = NULL;
+		if (!tcp_filter(sk, skb))
+			nsk = tcp_check_req(sk, skb, req, false);
 		if (!nsk) {
 			reqsk_put(req);
 			goto discard_and_relse;