net/smc: check variable before dereferencing in smc_close.c

smc->clcsock and smc->clcsock->sk are used before the check if they can
be dereferenced. Fix this by checking the variables first.

Fixes: a60a2b1e0af1 ("net/smc: reduce active tcp_listen workers")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index 10d05a6..0f9ffba 100644 (file)
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -208,11 +208,12 @@ again:
                break;
        case SMC_LISTEN:
                sk->sk_state = SMC_CLOSED;
-               smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
-               smc->clcsock->sk->sk_user_data = NULL;
                sk->sk_state_change(sk); /* wake up accept */
-               if (smc->clcsock && smc->clcsock->sk)
+               if (smc->clcsock && smc->clcsock->sk) {
+                       smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready;
+                       smc->clcsock->sk->sk_user_data = NULL;
                        rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
+               }
                smc_close_cleanup_listen(sk);
                release_sock(sk);
                flush_work(&smc->tcp_listen_work);