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authorPeter Hurley <peter@hurleysoftware.com>2014-02-09 20:59:15 -0500
committerMarcel Holtmann <marcel@holtmann.org>2014-02-14 13:39:31 -0800
commitb92483d54abb4ff288accc36bf1daef44dea9fbe (patch)
tree784f48a3535ba09ef487d580bc5a31d330ac246a /net/bluetooth/rfcomm
parentc4fd318d6ebc16bd64ca7b9c06f21b7f33bb462e (diff)
downloadblackbird-op-linux-b92483d54abb4ff288accc36bf1daef44dea9fbe.tar.gz
blackbird-op-linux-b92483d54abb4ff288accc36bf1daef44dea9fbe.zip
Bluetooth: Fix unsafe RFCOMM device parenting
Accessing the results of hci_conn_hash_lookup_ba() is unsafe without holding the hci_dev_lock() during the lookup. For example: CPU 0 | CPU 1 hci_conn_hash_lookup_ba | hci_conn_del rcu_read_lock | hci_conn_hash_del list_for_each_entry_rcu | list_del_rcu if (.....) | synchronize_rcu rcu_read_unlock | | hci_conn_del_sysfs | hci_dev_put | hci_conn_put | put_device (last reference) | bt_link_release | kfree(conn) return p << just freed | Even if a hci_conn reference were taken (via hci_conn_get), would not guarantee the lifetime of the sysfs device, but only safe access to the in-memory structure. Ensure the hci_conn device stays valid while the rfcomm device is reparented; rename rfcomm_get_device() to rfcomm_reparent_device() and perform the reparenting within the function while holding the hci_dev_lock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Tested-By: Alexander Holler <holler@ahsoftware.de> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net/bluetooth/rfcomm')
-rw-r--r--net/bluetooth/rfcomm/tty.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index a58d693e1e61..2975bc4b9188 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -167,20 +167,29 @@ static struct rfcomm_dev *rfcomm_dev_get(int id)
return dev;
}
-static struct device *rfcomm_get_device(struct rfcomm_dev *dev)
+static void rfcomm_reparent_device(struct rfcomm_dev *dev)
{
struct hci_dev *hdev;
struct hci_conn *conn;
hdev = hci_get_route(&dev->dst, &dev->src);
if (!hdev)
- return NULL;
+ return;
+ /* The lookup results are unsafe to access without the
+ * hci device lock (FIXME: why is this not documented?)
+ */
+ hci_dev_lock(hdev);
conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &dev->dst);
- hci_dev_put(hdev);
+ /* Just because the acl link is in the hash table is no
+ * guarantee the sysfs device has been added ...
+ */
+ if (conn && device_is_registered(&conn->dev))
+ device_move(dev->tty_dev, &conn->dev, DPM_ORDER_DEV_AFTER_PARENT);
- return conn ? &conn->dev : NULL;
+ hci_dev_unlock(hdev);
+ hci_dev_put(hdev);
}
static ssize_t show_address(struct device *tty_dev, struct device_attribute *attr, char *buf)
@@ -589,8 +598,7 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
dev->err = err;
if (dlc->state == BT_CONNECTED) {
- device_move(dev->tty_dev, rfcomm_get_device(dev),
- DPM_ORDER_DEV_AFTER_PARENT);
+ rfcomm_reparent_device(dev);
wake_up_interruptible(&dev->port.open_wait);
} else if (dlc->state == BT_CLOSED)
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