linux-kernel - [PATCH 3.16 330/346] Bluetooth: Fix potential NULL dereference in RFCOMM bind callback

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Message-ID: <lsq.1479082460.91108475@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Marcel Holtmann" <marcel@...tmann.org>,
        "Jaganath Kanakkassery" <jaganath.k@...sung.com>
Subject: [PATCH 3.16 330/346] Bluetooth: Fix potential NULL dereference in
 RFCOMM bind callback

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Jaganath Kanakkassery <jaganath.k@...sung.com>

commit 951b6a0717db97ce420547222647bcc40bf1eacd upstream.

addr can be NULL and it should not be dereferenced before NULL checking.

Signed-off-by: Jaganath Kanakkassery <jaganath.k@...sung.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/bluetooth/rfcomm/sock.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -334,16 +334,19 @@ static int rfcomm_sock_create(struct net
 
 static int rfcomm_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 {
-	struct sockaddr_rc *sa = (struct sockaddr_rc *) addr;
+	struct sockaddr_rc sa;
 	struct sock *sk = sock->sk;
-	int chan = sa->rc_channel;
-	int err = 0;
-
-	BT_DBG("sk %p %pMR", sk, &sa->rc_bdaddr);
+	int len, err = 0;
 
 	if (!addr || addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;
 
+	memset(&sa, 0, sizeof(sa));
+	len = min_t(unsigned int, sizeof(sa), addr_len);
+	memcpy(&sa, addr, len);
+
+	BT_DBG("sk %p %pMR", sk, &sa.rc_bdaddr);
+
 	lock_sock(sk);
 
 	if (sk->sk_state != BT_OPEN) {
@@ -358,12 +361,13 @@ static int rfcomm_sock_bind(struct socke
 
 	write_lock(&rfcomm_sk_list.lock);
 
-	if (chan && __rfcomm_get_listen_sock_by_addr(chan, &sa->rc_bdaddr)) {
+	if (sa.rc_channel &&
+	    __rfcomm_get_listen_sock_by_addr(sa.rc_channel, &sa.rc_bdaddr)) {
 		err = -EADDRINUSE;
 	} else {
 		/* Save source address */
-		bacpy(&rfcomm_pi(sk)->src, &sa->rc_bdaddr);
-		rfcomm_pi(sk)->channel = chan;
+		bacpy(&rfcomm_pi(sk)->src, &sa.rc_bdaddr);
+		rfcomm_pi(sk)->channel = sa.rc_channel;
 		sk->sk_state = BT_BOUND;
 	}