Bluetooth: Release rfcomm_dev only once
No logic prevents an rfcomm_dev from being released multiple
times. For example, if the rfcomm_dev ref count is large due
to pending tx, then multiple RFCOMMRELEASEDEV ioctls may
mistakenly release the rfcomm_dev too many times. Note that
concurrent ioctls are not required to create this condition.
Introduce RFCOMM_DEV_RELEASED status bit which guarantees the
rfcomm_dev can only be released once.
NB: Since the flags are exported to userspace, introduce the status
field to track state for which userspace should not be aware.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index c312cfc..b9759eb 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -324,11 +324,15 @@
#define RFCOMMGETDEVINFO _IOR('R', 211, int)
#define RFCOMMSTEALDLC _IOW('R', 220, int)
+/* rfcomm_dev.flags bit definitions */
#define RFCOMM_REUSE_DLC 0
#define RFCOMM_RELEASE_ONHUP 1
#define RFCOMM_HANGUP_NOW 2
#define RFCOMM_TTY_ATTACHED 3
-#define RFCOMM_TTY_RELEASED 4
+#define RFCOMM_DEFUNCT_BIT4 4 /* don't reuse this bit - userspace visible */
+
+/* rfcomm_dev.status bit definitions */
+#define RFCOMM_DEV_RELEASED 0
struct rfcomm_dev_req {
s16 dev_id;
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index b385d99..d9d4bc8 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -51,6 +51,8 @@
unsigned long flags;
int err;
+ unsigned long status; /* don't export to userspace */
+
bdaddr_t src;
bdaddr_t dst;
u8 channel;
@@ -423,6 +425,12 @@
return -EPERM;
}
+ /* only release once */
+ if (test_and_set_bit(RFCOMM_DEV_RELEASED, &dev->status)) {
+ tty_port_put(&dev->port);
+ return -EALREADY;
+ }
+
if (req.flags & (1 << RFCOMM_HANGUP_NOW))
rfcomm_dlc_close(dev->dlc, 0);
@@ -433,8 +441,7 @@
tty_kref_put(tty);
}
- if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags) &&
- !test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+ if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags))
tty_port_put(&dev->port);
tty_port_put(&dev->port);