linux-kernel - [PATCH 06/24] Bluetooth: Exclude released devices from RFCOMMGETDEVLIST ioctl

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Message-Id: <1391997564-1805-7-git-send-email-peter@hurleysoftware.com>
Date:	Sun,  9 Feb 2014 20:59:06 -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 06/24] Bluetooth: Exclude released devices from RFCOMMGETDEVLIST ioctl

When enumerating RFCOMM devices in the rfcomm_dev_list, holding
the rfcomm_dev_lock only guarantees the existence of the enumerated
rfcomm_dev in memory, and not safe access to its state. Testing
the device state (such as RFCOMM_TTY_RELEASED) does not guarantee
the device will remain in that state for the subsequent access
to the rfcomm_dev's fields, nor guarantee that teardown has not
commenced.

Obtain an rfcomm_dev reference for the duration of rfcomm_dev
access.

Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 net/bluetooth/rfcomm/tty.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 7cf193f..b385d99 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -468,7 +468,7 @@ static int rfcomm_get_dev_list(void __user *arg)
 	spin_lock(&rfcomm_dev_lock);
 
 	list_for_each_entry(dev, &rfcomm_dev_list, list) {
-		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+		if (!tty_port_get(&dev->port))
 			continue;
 		(di + n)->id      = dev->id;
 		(di + n)->flags   = dev->flags;
@@ -476,6 +476,7 @@ static int rfcomm_get_dev_list(void __user *arg)
 		(di + n)->channel = dev->channel;
 		bacpy(&(di + n)->src, &dev->src);
 		bacpy(&(di + n)->dst, &dev->dst);
+		tty_port_put(&dev->port);
 		if (++n >= dev_num)
 			break;
 	}
-- 
1.8.1.2

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