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@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 7cf193f0eea7..b385d9985656 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;
         }