diff -r 2aefd58f8ec5 -r 6ba2f471478b src/jdk.crypto.ec/share/classes/sun/security/ec/XDHKeyAgreement.java
--- a/src/jdk.crypto.ec/share/classes/sun/security/ec/XDHKeyAgreement.java	Wed Aug 29 14:48:09 2018 -0400
+++ b/src/jdk.crypto.ec/share/classes/sun/security/ec/XDHKeyAgreement.java	Thu Aug 30 11:08:01 2018 -0400
@@ -189,7 +189,7 @@
             throw new IllegalStateException("Not initialized correctly");
         }
         int secretLen = this.secret.length;
-        if (offset + secretLen > sharedSecret.length) {
+        if (secretLen > sharedSecret.length - offset) {
             throw new ShortBufferException("Need " + secretLen
                 + " bytes, only " + (sharedSecret.length - offset)
                 + " available");