linux-kernel - [PATCH 4.9 52/93] dccp: fix a memleak that dccp

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Message-Id: <20170809181337.771637041@linuxfoundation.org>
Date:   Wed,  9 Aug 2017 11:13:45 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jianlin Shi <jishi@...hat.com>,
        Xin Long <lucien.xin@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 52/93] dccp: fix a memleak that dccp_ipv6 doesnt put reqsk properly

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

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

From: Xin Long <lucien.xin@...il.com>

[ Upstream commit 0c2232b0a71db0ac1d22f751aa1ac0cadb950fd2 ]

In dccp_v6_conn_request, after reqsk gets alloced and hashed into
ehash table, reqsk's refcnt is set 3. one is for req->rsk_timer,
one is for hlist, and the other one is for current using.

The problem is when dccp_v6_conn_request returns and finishes using
reqsk, it doesn't put reqsk. This will cause reqsk refcnt leaks and
reqsk obj never gets freed.

Jianlin found this issue when running dccp_memleak.c in a loop, the
system memory would run out.

dccp_memleak.c:
  int s1 = socket(PF_INET6, 6, IPPROTO_IP);
  bind(s1, &sa1, 0x20);
  listen(s1, 0x9);
  int s2 = socket(PF_INET6, 6, IPPROTO_IP);
  connect(s2, &sa1, 0x20);
  close(s1);
  close(s2);

This patch is to put the reqsk before dccp_v6_conn_request returns,
just as what tcp_conn_request does.

Reported-by: Jianlin Shi <jishi@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/dccp/ipv6.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -380,6 +380,7 @@ static int dccp_v6_conn_request(struct s
 		goto drop_and_free;

 	inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
+	reqsk_put(req);
 	return 0;

 drop_and_free: