ppp: fix segfault in pppcp_send_code_reject()

fix memory corruption caused by misplaced paren when memcpying
rejected packet data into Code-Reject packet.

diff --git a/gatchat/ppp_cp.c b/gatchat/ppp_cp.c
index 137f6b9..39e872b 100644 (file)
--- a/gatchat/ppp_cp.c
+++ b/gatchat/ppp_cp.c
@@ -454,9 +454,12 @@ static void pppcp_send_code_reject(struct pppcp_data *data,
                                        guint8 *rejected_packet)
 {
        struct pppcp_packet *packet;
+       struct pppcp_packet *old_packet =
+                               (struct pppcp_packet *) rejected_packet;
 
-       packet = pppcp_packet_new(data, CODE_REJECT,
-                       ntohs(((struct pppcp_packet *) rejected_packet)->length));
+       pppcp_trace(data);
+
+       packet = pppcp_packet_new(data, CODE_REJECT, ntohs(old_packet->length));
 
        /*
         * Identifier must be changed for each Code-Reject sent
@@ -468,7 +471,7 @@ static void pppcp_send_code_reject(struct pppcp_data *data,
         * truncated if it needs to be to comply with mtu requirement
         */
        memcpy(packet->data, rejected_packet,
-                       ntohs(packet->length - CP_HEADER_SZ));
+                       ntohs(packet->length) - CP_HEADER_SZ);
 
        ppp_transmit(data->ppp, pppcp_to_ppp_packet(packet),
                        ntohs(packet->length));