s4:kdc: Don’t call memcpy() with a NULL pointer

Doing so is undefined behaviour.

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri May  5 03:52:30 UTC 2023 on atb-devel-224

diff --git a/source4/kdc/kpasswd-service.c b/source4/kdc/kpasswd-service.c
index 43dd8e0d866e09cfecd1dc037a6a1adbde535787..f8ca1e79498d1922375204ea9e32cf0e71a2fc64 100644 (file)
--- a/source4/kdc/kpasswd-service.c
+++ b/source4/kdc/kpasswd-service.c
@@ -379,9 +379,11 @@ reply:
        RSSVAL(reply->data, 0, reply->length);
        RSSVAL(reply->data, 2, 1);
        RSSVAL(reply->data, 4, ap_rep_blob.length);
-       memcpy(reply->data + HEADER_LEN,
-              ap_rep_blob.data,
-              ap_rep_blob.length);
+       if (ap_rep_blob.data != NULL) {
+               memcpy(reply->data + HEADER_LEN,
+                      ap_rep_blob.data,
+                      ap_rep_blob.length);
+       }
        memcpy(reply->data + HEADER_LEN + ap_rep_blob.length,
               enc_data_blob.data,
               enc_data_blob.length);