webrtcbin: Fix pointer dereference before null check

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3129>

diff --git a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
index ea33864..54a8c88 100644 (file)
--- a/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
+++ b/subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c
@@ -6366,6 +6366,12 @@ _set_description_task (GstWebRTCBin * webrtc, struct set_description *sd)
         continue;
       }
 
+      if (!pad->trans) {
+        GST_LOG_OBJECT (pad, "doesn't have a transceiver");
+        tmp = tmp->next;
+        continue;
+      }
+
       if (pad->trans->mline >= gst_sdp_message_medias_len (sd->sdp->sdp)) {
         GST_DEBUG_OBJECT (pad, "not mentioned in this description. Skipping");
         tmp = tmp->next;
@@ -6382,12 +6388,6 @@ _set_description_task (GstWebRTCBin * webrtc, struct set_description *sd)
         continue;
       }
 
-      if (!pad->trans) {
-        GST_LOG_OBJECT (pad, "doesn't have a transceiver");
-        tmp = tmp->next;
-        continue;
-      }
-
       new_dir = pad->trans->direction;
       if (new_dir != GST_WEBRTC_RTP_TRANSCEIVER_DIRECTION_SENDONLY &&
           new_dir != GST_WEBRTC_RTP_TRANSCEIVER_DIRECTION_SENDRECV) {