linux-kernel - [PATCH 3.18 13/50] Bluetooth: Fix potential NULL dereference

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Date:   Fri,  4 Aug 2017 16:15:59 -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,
        Patrik Flykt <patrik.flykt@...ux.intel.com>,
        Johan Hedberg <johan.hedberg@...el.com>,
        Marcel Holtmann <marcel@...tmann.org>
Subject: [PATCH 3.18 13/50] Bluetooth: Fix potential NULL dereference

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

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

From: Johan Hedberg <johan.hedberg@...el.com>

commit 88d9077c27d0c1a7c022d9dc987640beecf23560 upstream.

The bnep_get_device function may be triggered by an ioctl just after a
connection has gone down. In such a case the respective L2CAP chan->conn
pointer will get set to NULL (by l2cap_chan_del). This patch adds a
missing NULL check for this case in the bnep_get_device() function.

Reported-by: Patrik Flykt <patrik.flykt@...ux.intel.com>
Signed-off-by: Johan Hedberg <johan.hedberg@...el.com>
Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/bluetooth/bnep/core.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -511,13 +511,12 @@ static int bnep_session(void *arg)
 
 static struct device *bnep_get_device(struct bnep_session *session)
 {
-	struct hci_conn *conn;
+	struct l2cap_conn *conn = l2cap_pi(session->sock->sk)->chan->conn;
 
-	conn = l2cap_pi(session->sock->sk)->chan->conn->hcon;
-	if (!conn)
+	if (!conn || !conn->hcon)
 		return NULL;
 
-	return &conn->dev;
+	return &conn->hcon->dev;
 }
 
 static struct device_type bnep_type = {