In case the compression result is the same size as the orignal version,

the compression was useless as well.  Make sure to not update the data
and return, else we would waste resources when decompressing.

This also avoids the copyback() changing data other consumers like
xform_ipcomp.c would have ignored because of no win and sent out without
noting that compression was used, resulting in invalid packets at the
receiver.

MFC after:	5 days

sys/opencrypto/cryptosoft.c

@@ -552,7 +552,7 @@ swcr_compdec(struct cryptodesc *crd, struct swcr_data *sw,
 	sw->sw_size = result;
 	/* Check the compressed size when doing compression */
 	if (crd->crd_flags & CRD_F_COMP) {
-		if (result > crd->crd_len) {
+		if (result >= crd->crd_len) {
 			/* Compression was useless, we lost time */
 			free(out, M_CRYPTO_DATA);
 			return 0;