Fix for CVE-2014-0195

A buffer overrun attack can be triggered by sending invalid DTLS fragments
to an OpenSSL DTLS client or server. This is potentially exploitable to
run arbitrary code on a vulnerable client or server.

Fixed by adding consistency check for DTLS fragments.

Thanks to Jüri Aedla for reporting this issue.

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index 01d724211c3bbd95765db13f7d24565d488b9c7f..3426a0a5f330e3860e82658a914b8050d7f96b7e 100644 (file)
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -621,7 +621,16 @@ dtls1_reassemble_fragment(SSL *s, struct hm_header_st* msg_hdr, int *ok)
                frag->msg_header.frag_off = 0;
                }
        else
+               {
                frag = (hm_fragment*) item->data;
+               if (frag->msg_header.msg_len != msg_hdr->msg_len)
+                       {
+                       item = NULL;
+                       frag = NULL;
+                       goto err;
+                       }
+               }
+
 
        /* If message is already reassembled, this must be a
         * retransmit and can be dropped.