queue-4.14/lapb-fixed-leak-of-control-blocks.patch

   1 From foo@baz Wed 19 Jun 2019 04:01:16 PM CEST
   2 From: Jeremy Sowden <jeremy@azazel.net>
   3 Date: Sun, 16 Jun 2019 16:54:37 +0100
   4 Subject: lapb: fixed leak of control-blocks.
   5
   6 From: Jeremy Sowden <jeremy@azazel.net>
   7
   8 [ Upstream commit 6be8e297f9bcea666ea85ac7a6cd9d52d6deaf92 ]
   9
  10 lapb_register calls lapb_create_cb, which initializes the control-
  11 block's ref-count to one, and __lapb_insert_cb, which increments it when
  12 adding the new block to the list of blocks.
  13
  14 lapb_unregister calls __lapb_remove_cb, which decrements the ref-count
  15 when removing control-block from the list of blocks, and calls lapb_put
  16 itself to decrement the ref-count before returning.
  17
  18 However, lapb_unregister also calls __lapb_devtostruct to look up the
  19 right control-block for the given net_device, and __lapb_devtostruct
  20 also bumps the ref-count, which means that when lapb_unregister returns
  21 the ref-count is still 1 and the control-block is leaked.
  22
  23 Call lapb_put after __lapb_devtostruct to fix leak.
  24
  25 Reported-by: syzbot+afb980676c836b4a0afa@syzkaller.appspotmail.com
  26 Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
  27 Signed-off-by: David S. Miller <davem@davemloft.net>
  28 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  29 ---
  30  net/lapb/lapb_iface.c |    1 +
  31  1 file changed, 1 insertion(+)
  32
  33 --- a/net/lapb/lapb_iface.c
  34 +++ b/net/lapb/lapb_iface.c
  35 @@ -182,6 +182,7 @@ int lapb_unregister(struct net_device *d
  36         lapb = __lapb_devtostruct(dev);
  37         if (!lapb)
  38                 goto out;
  39 +       lapb_put(lapb);
  40
  41         lapb_stop_t1timer(lapb);
  42         lapb_stop_t2timer(lapb);