diff --git a/app/test/test_cryptodev_blockcipher.c b/app/test/test_cryptodev_blockcipher.c
index 37b10cf..1757c76 100644
--- a/app/test/test_cryptodev_blockcipher.c
+++ b/app/test/test_cryptodev_blockcipher.c
@@ -45,6 +45,7 @@
 #include "test_cryptodev_aes_test_vectors.h"
 #include "test_cryptodev_des_test_vectors.h"
 #include "test_cryptodev_hash_test_vectors.h"
+#include "test_cryptodev.h"
 
 static int
 test_blockcipher_one_case(const struct blockcipher_test_case *t,
@@ -71,6 +72,10 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 	uint32_t buf_len = tdata->ciphertext.len;
 	uint32_t digest_len = 0;
 	char *buf_p = NULL;
+	uint8_t src_pattern = 0xa5;
+	uint8_t dst_pattern = 0xb6;
+	uint8_t tmp_src_buf[MBUF_SIZE];
+	uint8_t tmp_dst_buf[MBUF_SIZE];
 
 	if (tdata->cipher_key.len)
 		memcpy(cipher_key, tdata->cipher_key.data,
@@ -104,6 +109,7 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 		status = TEST_FAILED;
 		goto error_exit;
 	}
+	memset(ibuf->buf_addr, src_pattern, ibuf->buf_len);
 
 	if (t->op_mask & BLOCKCIPHER_TEST_OP_CIPHER)
 		buf_len += tdata->iv.len;
@@ -152,6 +158,7 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 			status = TEST_FAILED;
 			goto error_exit;
 		}
+		memset(obuf->buf_addr, dst_pattern, obuf->buf_len);
 
 		buf_p = rte_pktmbuf_append(obuf, buf_len);
 		if (!buf_p) {
@@ -342,6 +349,17 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 		rte_crypto_op_attach_sym_session(op, sess);
 	}
 
+	TEST_HEXDUMP(stdout, "m_src(before):",
+			sym_op->m_src->buf_addr, sym_op->m_src->buf_len);
+	rte_memcpy(tmp_src_buf, sym_op->m_src->buf_addr,
+						sym_op->m_src->buf_len);
+	if (t->feature_mask & BLOCKCIPHER_TEST_FEATURE_OOP) {
+		TEST_HEXDUMP(stdout, "m_dst(before):",
+			sym_op->m_dst->buf_addr, sym_op->m_dst->buf_len);
+		rte_memcpy(tmp_dst_buf, sym_op->m_dst->buf_addr,
+						sym_op->m_dst->buf_len);
+	}
+
 	/* Process crypto operation */
 	if (rte_cryptodev_enqueue_burst(dev_id, 0, &op, 1) != 1) {
 		snprintf(test_msg, BLOCKCIPHER_TEST_MSG_LEN,
@@ -364,12 +382,11 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 		goto error_exit;
 	}
 
-	TEST_HEXDUMP(stdout, "m_src:",
-		rte_pktmbuf_mtod(sym_op->m_src, uint8_t *), buf_len);
+	TEST_HEXDUMP(stdout, "m_src(after):",
+			sym_op->m_src->buf_addr, sym_op->m_src->buf_len);
 	if (t->feature_mask & BLOCKCIPHER_TEST_FEATURE_OOP)
-		TEST_HEXDUMP(stdout, "m_dst:",
-			rte_pktmbuf_mtod(sym_op->m_dst, uint8_t *),
-			buf_len);
+		TEST_HEXDUMP(stdout, "m_dst(after):",
+			sym_op->m_dst->buf_addr, sym_op->m_dst->buf_len);
 
 	/* Verify results */
 	if (op->status != RTE_CRYPTO_OP_STATUS_SUCCESS) {
@@ -430,6 +447,118 @@ test_blockcipher_one_case(const struct blockcipher_test_case *t,
 		}
 	}
 
+	/* The only parts that should have changed in the buffer are
+	 * plaintext/ciphertext and digest.
+	 * In OOP only the dest buffer should change.
+	 */
+	if (t->feature_mask & BLOCKCIPHER_TEST_FEATURE_OOP) {
+		struct rte_mbuf *mbuf;
+		uint8_t value;
+		uint32_t head_unchanged_len = 0, changed_len = 0;
+		uint32_t i;
+
+		mbuf = sym_op->m_src;
+		if (t->op_mask & BLOCKCIPHER_TEST_OP_AUTH_VERIFY) {
+			/* white-box test: PMDs use some of the
+			 * tailroom as temp storage in verify case
+			 */
+			head_unchanged_len = rte_pktmbuf_headroom(mbuf)
+					+ rte_pktmbuf_data_len(mbuf);
+			changed_len = digest_len;
+		} else {
+			head_unchanged_len = mbuf->buf_len;
+			changed_len = 0;
+		}
+
+		for (i = 0; i < mbuf->buf_len; i++) {
+			if (i == head_unchanged_len)
+				i += changed_len;
+			value = *((uint8_t *)(mbuf->buf_addr)+i);
+			if (value != tmp_src_buf[i]) {
+				snprintf(test_msg, BLOCKCIPHER_TEST_MSG_LEN,
+	"line %u FAILED: OOP src outer mbuf data (0x%x) not as expected (0x%x)",
+					__LINE__, value, tmp_src_buf[i]);
+				status = TEST_FAILED;
+				goto error_exit;
+			}
+		}
+
+		mbuf = sym_op->m_dst;
+		if (t->op_mask & BLOCKCIPHER_TEST_OP_AUTH) {
+			head_unchanged_len = rte_pktmbuf_headroom(mbuf) +
+						sym_op->auth.data.offset;
+			changed_len = sym_op->auth.data.length;
+			if (t->op_mask & BLOCKCIPHER_TEST_OP_AUTH_GEN)
+				changed_len += sym_op->auth.digest.length;
+		} else {
+			/* cipher-only */
+			head_unchanged_len = rte_pktmbuf_headroom(mbuf) +
+					sym_op->cipher.data.offset;
+			changed_len = sym_op->cipher.data.length;
+		}
+
+		for (i = 0; i < mbuf->buf_len; i++) {
+			if (i == head_unchanged_len)
+				i += changed_len;
+			value = *((uint8_t *)(mbuf->buf_addr)+i);
+			if (value != tmp_dst_buf[i]) {
+				snprintf(test_msg, BLOCKCIPHER_TEST_MSG_LEN,
+	"line %u FAILED: OOP dst outer mbuf data (0x%x) not as expected (0x%x)",
+					__LINE__, value, tmp_dst_buf[i]);
+				status = TEST_FAILED;
+				goto error_exit;
+			}
+		}
+	} else {
+		/* In-place operation */
+		struct rte_mbuf *mbuf;
+		uint8_t value;
+		uint32_t head_unchanged_len = 0, changed_len = 0;
+		uint32_t i;
+
+		mbuf = sym_op->m_src;
+		if (t->op_mask & BLOCKCIPHER_TEST_OP_CIPHER) {
+			head_unchanged_len = rte_pktmbuf_headroom(mbuf) +
+					sym_op->cipher.data.offset;
+			changed_len = sym_op->cipher.data.length;
+		} else {
+			/* auth-only */
+			head_unchanged_len = rte_pktmbuf_headroom(mbuf) +
+					sym_op->auth.data.offset +
+					sym_op->auth.data.length;
+			changed_len = 0;
+		}
+
+		if (t->op_mask & BLOCKCIPHER_TEST_OP_AUTH_GEN)
+			changed_len += sym_op->auth.digest.length;
+
+		if (t->op_mask & BLOCKCIPHER_TEST_OP_AUTH_VERIFY) {
+			/* white-box test: PMDs use some of the
+			 * tailroom as temp storage in verify case
+			 */
+			if (t->op_mask & BLOCKCIPHER_TEST_OP_CIPHER) {
+				/* This is simplified, not checking digest*/
+				changed_len += digest_len*2;
+			} else {
+				head_unchanged_len += digest_len;
+				changed_len += digest_len;
+			}
+		}
+
+		for (i = 0; i < mbuf->buf_len; i++) {
+			if (i == head_unchanged_len)
+				i += changed_len;
+			value = *((uint8_t *)(mbuf->buf_addr)+i);
+			if (value != tmp_src_buf[i]) {
+				snprintf(test_msg, BLOCKCIPHER_TEST_MSG_LEN,
+		"line %u FAILED: outer mbuf data (0x%x) not as expected (0x%x)",
+					__LINE__, value, tmp_src_buf[i]);
+				status = TEST_FAILED;
+				goto error_exit;
+			}
+		}
+	}
+
 	snprintf(test_msg, BLOCKCIPHER_TEST_MSG_LEN, "PASS");
 
 error_exit:
