diff --git a/test-tool/test_extendedcopy_descr_limits.c b/test-tool/test_extendedcopy_descr_limits.c
index e2cf59e..24e9cbf 100644
--- a/test-tool/test_extendedcopy_descr_limits.c
+++ b/test-tool/test_extendedcopy_descr_limits.c
@@ -82,6 +82,7 @@ test_extendedcopy_descr_limits(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(alloc_len);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, alloc_len);
 
 	logging(LOG_VERBOSE,
 			"Test sending more than supported target descriptors");
diff --git a/test-tool/test_extendedcopy_descr_type.c b/test-tool/test_extendedcopy_descr_type.c
index 28c0572..74e134e 100644
--- a/test-tool/test_extendedcopy_descr_type.c
+++ b/test-tool/test_extendedcopy_descr_type.c
@@ -64,6 +64,7 @@ test_extendedcopy_descr_type(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(alloc_len);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, alloc_len);
 
 	logging(LOG_VERBOSE,
 			"Send Fibre Channel N_Port_Name target descriptor");
diff --git a/test-tool/test_extendedcopy_param.c b/test-tool/test_extendedcopy_param.c
index ee5d4db..d6e251e 100644
--- a/test-tool/test_extendedcopy_param.c
+++ b/test-tool/test_extendedcopy_param.c
@@ -44,6 +44,7 @@ test_extendedcopy_param(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(data.size);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, data.size);
 
 	offset += populate_tgt_desc(xcopybuf+offset, IDENT_DESCR_TGT_DESCR,
 			LU_ID_TYPE_LUN, 0, 0, 0, 0, sd);
diff --git a/test-tool/test_extendedcopy_simple.c b/test-tool/test_extendedcopy_simple.c
index f40128a..aaa283a 100644
--- a/test-tool/test_extendedcopy_simple.c
+++ b/test-tool/test_extendedcopy_simple.c
@@ -58,6 +58,7 @@ test_extendedcopy_simple(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(data.size);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, data.size);
 
 	/* Initialize target descriptor list with one target descriptor */
 	offset += populate_tgt_desc(xcopybuf+offset, IDENT_DESCR_TGT_DESCR,
diff --git a/test-tool/test_extendedcopy_validate_seg_descr.c b/test-tool/test_extendedcopy_validate_seg_descr.c
index 36208f7..51a0648 100644
--- a/test-tool/test_extendedcopy_validate_seg_descr.c
+++ b/test-tool/test_extendedcopy_validate_seg_descr.c
@@ -44,6 +44,7 @@ test_extendedcopy_validate_seg_descr(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(data.size);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, data.size);
 
 	logging(LOG_VERBOSE, "Send invalid target descriptor index");
 	offset += populate_tgt_desc(xcopybuf+offset, IDENT_DESCR_TGT_DESCR,
diff --git a/test-tool/test_extendedcopy_validate_tgt_descr.c b/test-tool/test_extendedcopy_validate_tgt_descr.c
index ec197c7..fc9c86a 100644
--- a/test-tool/test_extendedcopy_validate_tgt_descr.c
+++ b/test-tool/test_extendedcopy_validate_tgt_descr.c
@@ -44,6 +44,7 @@ test_extendedcopy_validate_tgt_descr(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(data.size);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, data.size);
 
 	logging(LOG_VERBOSE, "Unsupported LU_ID TYPE");
 	/* Unsupported LU ID TYPE */
diff --git a/test-tool/test_receive_copy_results_copy_status.c b/test-tool/test_receive_copy_results_copy_status.c
index d76d01e..05404b9 100644
--- a/test-tool/test_receive_copy_results_copy_status.c
+++ b/test-tool/test_receive_copy_results_copy_status.c
@@ -57,6 +57,7 @@ test_receive_copy_results_copy_status(void)
 		get_desc_len(BLK_TO_BLK_SEG_DESCR);
 	data.data = alloca(data.size);
 	xcopybuf = data.data;
+	memset(xcopybuf, 0, data.size);
 
 	/* Initialize target descriptor list with one target descriptor */
 	offset += populate_tgt_desc(xcopybuf+offset, IDENT_DESCR_TGT_DESCR,
diff --git a/test-tool/test_writeatomic16_beyond_eol.c b/test-tool/test_writeatomic16_beyond_eol.c
index 5308d72..5e27b0b 100644
--- a/test-tool/test_writeatomic16_beyond_eol.c
+++ b/test-tool/test_writeatomic16_beyond_eol.c
@@ -29,7 +29,8 @@ void
 test_writeatomic16_beyond_eol(void)
 {
 	int align, i, gran, ret;
-	unsigned char *buf = alloca(256 * 2 * block_size);
+	const size_t bufsz = 256 * 2 * block_size;
+	unsigned char *buf = alloca(bufsz);
 
 
 	CHECK_FOR_DATALOSS;
@@ -42,6 +43,7 @@ test_writeatomic16_beyond_eol(void)
 
 	logging(LOG_VERBOSE, LOG_BLANK_LINE);
 
+	memset(buf, 0xa6, bufsz);
 	align = inq_bl->atomic_align ? inq_bl->atomic_align : 1;
 	gran = inq_bl->atomic_gran ? inq_bl->atomic_gran : 1;
 	ret = writeatomic16(sd, 0,
@@ -56,7 +58,6 @@ test_writeatomic16_beyond_eol(void)
 	CU_ASSERT_EQUAL(ret, 0);
 
 	logging(LOG_VERBOSE, "Test WRITEATOMIC16 1-256 blocks <granularity> blocks beyond the end");
-	memset(buf, 0xa6, 256 * block_size);
 	for (i = gran; i <= 256; i += gran) {
 		if (maximum_transfer_length && maximum_transfer_length < i) {
 			break;
diff --git a/test-tool/test_writeatomic16_simple.c b/test-tool/test_writeatomic16_simple.c
index 45a30d3..b197d02 100644
--- a/test-tool/test_writeatomic16_simple.c
+++ b/test-tool/test_writeatomic16_simple.c
@@ -30,7 +30,8 @@ void
 test_writeatomic16_simple(void)
 {
 	int i, gran, ret;
-	unsigned char *buf = alloca(256 * block_size);
+	const size_t bufsz = 256 * block_size;
+	unsigned char *buf = alloca(bufsz);
 
 
 	CHECK_FOR_DATALOSS;
@@ -43,6 +44,7 @@ test_writeatomic16_simple(void)
 
 	logging(LOG_VERBOSE, LOG_BLANK_LINE);
 
+	memset(buf, 0, bufsz);
 	gran = inq_bl->atomic_gran ? inq_bl->atomic_gran : 1;
 	ret = writeatomic16(sd, 0,
 			    block_size * gran,
diff --git a/test-tool/test_writeatomic16_wrprotect.c b/test-tool/test_writeatomic16_wrprotect.c
index 900e295..b09d5e4 100644
--- a/test-tool/test_writeatomic16_wrprotect.c
+++ b/test-tool/test_writeatomic16_wrprotect.c
@@ -43,6 +43,7 @@ test_writeatomic16_wrprotect(void)
 	logging(LOG_VERBOSE, LOG_BLANK_LINE);
 
 	gran = inq_bl->atomic_gran ? inq_bl->atomic_gran : 1;
+	memset(buf, 0, block_size);
 	ret = writeatomic16(sd, 0,
 			    block_size * gran,
 			    block_size, 0, 0, 0, 0, buf,