sctp: asconf's process should verify address parameter is in the beginning

in sctp_process_asconf(), we get address parameter from the beginning of
the addip params. but we never check if it's really there. if the addr
param is not there, it still can pass sctp_verify_asconf(), then to be
handled by sctp_process_asconf(), it will not be safe.

so add a code in sctp_verify_asconf() to check the address parameter is in
the beginning, or return false to send abort.

note that this can also detect multiple address parameters, and reject it.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 06320c8..a655ddc 100644 (file)
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -3132,11 +3132,18 @@ bool sctp_verify_asconf(const struct sctp_association *asoc,
                case SCTP_PARAM_IPV4_ADDRESS:
                        if (length != sizeof(sctp_ipv4addr_param_t))
                                return false;
+                       /* ensure there is only one addr param and it's in the
+                        * beginning of addip_hdr params, or we reject it.
+                        */
+                       if (param.v != addip->addip_hdr.params)
+                               return false;
                        addr_param_seen = true;
                        break;
                case SCTP_PARAM_IPV6_ADDRESS:
                        if (length != sizeof(sctp_ipv6addr_param_t))
                                return false;
+                       if (param.v != addip->addip_hdr.params)
+                               return false;
                        addr_param_seen = true;
                        break;
                case SCTP_PARAM_ADD_IP: