From 95782ada1f4bed83472bc3bc7e464d07a49fb3ae Mon Sep 17 00:00:00 2001 From: Jon Simons Date: Thu, 30 Jan 2014 18:30:41 -0800 Subject: [PATCH] socket: fix read of non-connected socket Ensure to check whether the socket at hand is indeed still connected throughout POLLIN processing in ssh_socket_pollcallback. Before this change, the POLLIN block in ssh_socket_pollcallback is predicated against the condition (s->state == SSH_SOCKET_CONNECTED). Once entered, data from the socket is consumed through the data callback in this loop: do { r = s->callbacks->data(buffer_get_rest(s->in_buffer), buffer_get_rest_len(s->in_buffer), s->callbacks->userdata); buffer_pass_bytes(s->in_buffer,r); } while (r > 0); However, it is possible for the socket data callback to change the state of the socket (closing it, for example). Fix the loop to only continue so long as the socket remains connected: this also entails setting the ssh_socket state to SSH_SOCKET_CLOSED upon close. The bug can be observed before the change by sending a bogus banner to the server: 'echo -e "A\r\nB\r\n" | nc localhost 22'. Each of 'A' and 'B' will be processed by 'callback_receive_banner', even though the client socket is closed after rejection of 'A'. Reviewed-by: Andreas Schneider --- src/socket.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/socket.c b/src/socket.c index 935137c1..8f4c9b22 100644 --- a/src/socket.c +++ b/src/socket.c @@ -291,7 +291,7 @@ int ssh_socket_pollcallback(struct ssh_poll_handle_struct *p, socket_t fd, int r buffer_get_rest_len(s->in_buffer), s->callbacks->userdata); buffer_pass_bytes(s->in_buffer,r); - } while (r > 0); + } while ((r > 0) && (s->state == SSH_SOCKET_CONNECTED)); /* p may have been freed, so don't use it * anymore in this function */ p = NULL; @@ -440,6 +440,8 @@ void ssh_socket_close(ssh_socket s){ ssh_poll_free(s->poll_out); s->poll_out=NULL; } + + s->state = SSH_SOCKET_CLOSED; } /**