net/smc: fix double kfree in smc_listen_work()

If smc_listen_rmda_finish() returns with an error, the storage
addressed by 'buf' is freed a second time.
Consolidate freeing under a common label and jump to that label.

Fixes: 6bb14e48 ("net/smc: dynamic allocation of CLC proposal buffer")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: NKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -1371,7 +1371,6 @@ static void smc_listen_work(struct work_struct *work)
 	}
 
 	/* finish worker */
-	kfree(buf);
 	if (!ism_supported) {
 		rc = smc_listen_rdma_finish(new_smc, &cclc,
 					    ini.first_contact_local);
@@ -1381,12 +1380,13 @@ static void smc_listen_work(struct work_struct *work)
 	}
 	smc_conn_save_peer_info(new_smc, &cclc);
 	smc_listen_out_connected(new_smc);
-	return;
+	goto out_free;
 
 out_unlock:
 	mutex_unlock(&smc_server_lgr_pending);
 out_decl:
 	smc_listen_decline(new_smc, rc, ini.first_contact_local);
+out_free:
 	kfree(buf);
 }