linux-kernel - [PATCH 4.4 38/97] netfilter: xt_CT: fix refcnt leak on error path

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Date:   Fri, 23 Mar 2018 10:54:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Gao Feng <fgao@...ai8.com>,
        Liping Zhang <zlpnobody@...il.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.4 38/97] netfilter: xt_CT: fix refcnt leak on error path

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

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

From: Gao Feng <fgao@...ai8.com>


[ Upstream commit 470acf55a021713869b9bcc967268ac90c8a0fac ]

There are two cases which causes refcnt leak.

1. When nf_ct_timeout_ext_add failed in xt_ct_set_timeout, it should
free the timeout refcnt.
Now goto the err_put_timeout error handler instead of going ahead.

2. When the time policy is not found, we should call module_put.
Otherwise, the related cthelper module cannot be removed anymore.
It is easy to reproduce by typing the following command:
  # iptables -t raw -A OUTPUT -p tcp -j CT --helper ftp --timeout xxx

Signed-off-by: Gao Feng <fgao@...ai8.com>
Signed-off-by: Liping Zhang <zlpnobody@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netfilter/xt_CT.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -168,8 +168,10 @@ xt_ct_set_timeout(struct nf_conn *ct, co
 		goto err_put_timeout;
 	}
 	timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
-	if (timeout_ext == NULL)
+	if (!timeout_ext) {
 		ret = -ENOMEM;
+		goto err_put_timeout;
+	}
 
 	rcu_read_unlock();
 	return ret;
@@ -201,6 +203,7 @@ static int xt_ct_tg_check(const struct x
 			  struct xt_ct_target_info_v1 *info)
 {
 	struct nf_conntrack_zone zone;
+	struct nf_conn_help *help;
 	struct nf_conn *ct;
 	int ret = -EOPNOTSUPP;
 
@@ -249,7 +252,7 @@ static int xt_ct_tg_check(const struct x
 	if (info->timeout[0]) {
 		ret = xt_ct_set_timeout(ct, par, info->timeout);
 		if (ret < 0)
-			goto err3;
+			goto err4;
 	}
 	__set_bit(IPS_CONFIRMED_BIT, &ct->status);
 	nf_conntrack_get(&ct->ct_general);
@@ -257,6 +260,10 @@ out:
 	info->ct = ct;
 	return 0;
 
+err4:
+	help = nfct_help(ct);
+	if (help)
+		module_put(help->helper->me);
 err3:
 	nf_ct_tmpl_free(ct);
 err2: