diff --git a/test-tool/iscsi-support.c b/test-tool/iscsi-support.c
index 889abbc..ca1ea8d 100644
--- a/test-tool/iscsi-support.c
+++ b/test-tool/iscsi-support.c
@@ -224,7 +224,8 @@ static struct scsi_task *send_scsi_command(struct scsi_device *sdev, struct scsi
 		case SCSI_XFER_READ:
 		  io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
 		  task->datain.size = task->expxferlen;
-		  task->datain.data = malloc(task->expxferlen);
+		  task->datain.data = malloc(task->datain.size);
+		  memset(task->datain.data, 0, task->datain.size);
 		  io_hdr.dxferp = task->datain.data;
 		  io_hdr.dxfer_len = task->datain.size;
 		  break;