[PATCH 7.0 25/49] rose: fix netdev double-hold in rose_make_new()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

7.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bernard Pidoux <bernard.f6bvp@gmail.com>

commit b9fb21ceb4f0d043767a1eba60786ec84809033b upstream.

rose_make_new() copies orose->device from the listener socket and calls
netdev_hold(), storing the tracker in rose->dev_tracker.  The only
caller, rose_rx_call_request(), then overwrites both make_rose->device
and make_rose->dev_tracker with a fresh netdev_hold() for the actual
incoming-call device.

This orphans the tracker allocated by rose_make_new(): it remains in
the device's refcount_tracker list but no pointer exists to free it
via netdev_put().  The result is one spurious outstanding reference per
accepted CALL_REQUEST, visible at rmmod time as:

  ref_tracker: netdev@X has 2/2 users at
      rose_rx_call_request+0xba3/0x1d50 [rose]
      rose_loopback_timer+0x3eb/0x670 [rose]

The second entry is the orphaned tracker from rose_make_new(); the
first is the correctly-managed socket reference from rose_rx_call_request().

Fix: initialise rose->device to NULL in rose_make_new() and let
rose_rx_call_request() -- the sole caller -- assign the correct device
and take the sole netdev_hold() as it already does.

Signed-off-by: Bernard Pidoux <bernard.f6bvp@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/rose/af_rose.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -631,9 +631,7 @@ static struct sock *rose_make_new(struct
 	rose->hb	= orose->hb;
 	rose->idle	= orose->idle;
 	rose->defer	= orose->defer;
-	rose->device	= orose->device;
-	if (rose->device)
-		netdev_hold(rose->device, &rose->dev_tracker, GFP_ATOMIC);
+	rose->device	= NULL;  /* rose_rx_call_request() sets this */
 	rose->qbitincl	= orose->qbitincl;
 
 	return sk;