packet.c: improved parsing in packet_x11_open
Use new API to parse data in packet_x11_open() for better bounds checking.
@@ -295,21 +295,56 @@ packet_x11_open(LIBSSH2_SESSION * session, unsigned char *data,
LIBSSH2_CHANNEL *channel = x11open_state->channel;
int rc;
- (void) datalen;
-
if(x11open_state->state == libssh2_NB_state_idle) {
- unsigned char *s = data + (sizeof("x11") - 1) + 5;
- x11open_state->sender_channel = _libssh2_ntohu32(s);
- s += 4;
- x11open_state->initial_window_size = _libssh2_ntohu32(s);
- s += 4;
- x11open_state->packet_size = _libssh2_ntohu32(s);
- s += 4;
- x11open_state->shost_len = _libssh2_ntohu32(s);
- s += 4;
- x11open_state->shost = s;
- s += x11open_state->shost_len;
- x11open_state->sport = _libssh2_ntohu32(s);
+
+ unsigned long offset = (sizeof("x11") - 1) + 5;
+ size_t temp_len = 0;
+ struct string_buf buf;
+ buf.data = data;
+ buf.dataptr = buf.data;
+ buf.len = datalen;
+
+ if(datalen < offset) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected data length");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
+
+ buf.dataptr += offset;
+
+ if(_libssh2_get_u32(&buf, &(x11open_state->sender_channel))) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected sender channel size");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
+ if(_libssh2_get_u32(&buf, &(x11open_state->initial_window_size))) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected window size");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
+ if(_libssh2_get_u32(&buf, &(x11open_state->packet_size))) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected window size");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
+ if(_libssh2_get_string(&buf, &(x11open_state->shost), &temp_len)) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected host size");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
+ x11open_state->shost_len = (uint32_t)temp_len;
+
+ if(_libssh2_get_u32(&buf, &(x11open_state->sport))) {
+ _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+ "unexpected port size");
+ failure_code = SSH_OPEN_CONNECT_FAILED;
+ goto x11_exit;
+ }
_libssh2_debug(session, LIBSSH2_TRACE_CONN,
"X11 Connection Received from %s:%ld on channel %lu",
