session: Avoid potential null dereference on low-memory conditions

CID 1500478

Thanks coverity

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Norbert Pocs <npocs@redhat.com>
(cherry picked from commit ebea7d9023)

src/session.c

@@ -663,6 +663,10 @@ int ssh_handle_packets(ssh_session session, int timeout)
     }
 
     spoll = ssh_socket_get_poll_handle(session->socket);
+    if (spoll == NULL) {
+        ssh_set_error_oom(session);
+        return SSH_ERROR;
+    }
     ssh_poll_add_events(spoll, POLLIN);
     ctx = ssh_poll_get_ctx(spoll);