linux-kernel - [PATCH 18/24] Bluetooth: Serialize RFCOMMCREATEDEV and RFCOMMRELEASEDEV ioctls

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Date:	Sun,  9 Feb 2014 20:59:18 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	Marcel Holtmann <marcel@...tmann.org>
Cc:	Gustavo Padovan <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	Gianluca Anzolin <gianluca@...tospazio.it>,
	Alexander Holler <holler@...oftware.de>,
	Andrey Vihrov <andrey.vihrov@...il.com>,
	Sander Eikelenboom <linux@...elenboom.it>,
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
	Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH 18/24] Bluetooth: Serialize RFCOMMCREATEDEV and RFCOMMRELEASEDEV ioctls

At least two different race conditions exist with multiple concurrent
RFCOMMCREATEDEV and RFCOMMRELEASEDEV ioctls:
* Multiple concurrent RFCOMMCREATEDEVs with RFCOMM_REUSE_DLC can
  mistakenly share the same DLC.
* RFCOMMRELEASEDEV can destruct the rfcomm_dev still being
  constructed by RFCOMMCREATEDEV.

Introduce rfcomm_ioctl_mutex to serialize these add/remove operations.

Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 net/bluetooth/rfcomm/tty.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 4a38b54..ef27695 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -40,6 +40,7 @@
 #define RFCOMM_TTY_MAJOR 216		/* device node major id of the usb/bluetooth.c driver */
 #define RFCOMM_TTY_MINOR 0
 
+static DEFINE_MUTEX(rfcomm_ioctl_mutex);
 static struct tty_driver *rfcomm_tty_driver;
 
 struct rfcomm_dev {
@@ -373,7 +374,7 @@ static struct sk_buff *rfcomm_wmalloc(struct rfcomm_dev *dev, unsigned long size
 
 #define NOCAP_FLAGS ((1 << RFCOMM_REUSE_DLC) | (1 << RFCOMM_RELEASE_ONHUP))
 
-static int rfcomm_create_dev(struct sock *sk, void __user *arg)
+static int __rfcomm_create_dev(struct sock *sk, void __user *arg)
 {
 	struct rfcomm_dev_req req;
 	struct rfcomm_dlc *dlc;
@@ -423,7 +424,7 @@ static int rfcomm_create_dev(struct sock *sk, void __user *arg)
 	return id;
 }
 
-static int rfcomm_release_dev(void __user *arg)
+static int __rfcomm_release_dev(void __user *arg)
 {
 	struct rfcomm_dev_req req;
 	struct rfcomm_dev *dev;
@@ -466,6 +467,28 @@ static int rfcomm_release_dev(void __user *arg)
 	return 0;
 }
 
+static int rfcomm_create_dev(struct sock *sk, void __user *arg)
+{
+	int ret;
+
+	mutex_lock(&rfcomm_ioctl_mutex);
+	ret = __rfcomm_create_dev(sk, arg);
+	mutex_unlock(&rfcomm_ioctl_mutex);
+
+	return ret;
+}
+
+static int rfcomm_release_dev(void __user *arg)
+{
+	int ret;
+
+	mutex_lock(&rfcomm_ioctl_mutex);
+	ret = __rfcomm_release_dev(arg);
+	mutex_unlock(&rfcomm_ioctl_mutex);
+
+	return ret;
+}
+
 static int rfcomm_get_dev_list(void __user *arg)
 {
 	struct rfcomm_dev *dev;
-- 
1.8.1.2

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