git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From c0f3f01e29cf2a07bf7fd78c441100782c31a8be Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Mon, 7 Sep 2020 14:31:48 +0800
   4 Subject: can: j1939: j1939_sk_bind(): return failure if netdev is down
   5
   6 From: Zhang Changzhong <zhangchangzhong@huawei.com>
   7
   8 [ Upstream commit 08c487d8d807535f509ed80c6a10ad90e6872139 ]
   9
  10 When a netdev down event occurs after a successful call to
  11 j1939_sk_bind(), j1939_netdev_notify() can handle it correctly.
  12
  13 But if the netdev already in down state before calling j1939_sk_bind(),
  14 j1939_sk_release() will stay in wait_event_interruptible() blocked
  15 forever. Because in this case, j1939_netdev_notify() won't be called and
  16 j1939_tp_txtimer() won't call j1939_session_cancel() or other function
  17 to clear session for ENETDOWN error, this lead to mismatch of
  18 j1939_session_get/put() and jsk->skb_pending will never decrease to
  19 zero.
  20
  21 To reproduce it use following commands:
  22 1. ip link add dev vcan0 type vcan
  23 2. j1939acd -r 100,80-120 1122334455667788 vcan0
  24 3. presses ctrl-c and thread will be blocked forever
  25
  26 This patch adds check for ndev->flags in j1939_sk_bind() to avoid this
  27 kind of situation and return with -ENETDOWN.
  28
  29 Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
  30 Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
  31 Link: https://lore.kernel.org/r/1599460308-18770-1-git-send-email-zhangchangzhong@huawei.com
  32 Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
  33 Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
  34 Signed-off-by: Sasha Levin <sashal@kernel.org>
  35 ---
  36  net/can/j1939/socket.c | 6 ++++++
  37  1 file changed, 6 insertions(+)
  38
  39 diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
  40 index bf9fd6ee88fe0..0470909605392 100644
  41 --- a/net/can/j1939/socket.c
  42 +++ b/net/can/j1939/socket.c
  43 @@ -475,6 +475,12 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
  44                         goto out_release_sock;
  45                 }
  46
  47 +               if (!(ndev->flags & IFF_UP)) {
  48 +                       dev_put(ndev);
  49 +                       ret = -ENETDOWN;
  50 +                       goto out_release_sock;
  51 +               }
  52 +
  53                 priv = j1939_netdev_start(ndev);
  54                 dev_put(ndev);
  55                 if (IS_ERR(priv)) {
  56 --
  57 2.27.0
  58