diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 6865b186f749..9371194677dc 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1685,8 +1685,7 @@ static void free_params(struct dm_ioctl *param, size_t param_size, int param_fla
 }
 
 static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
-		       int ioctl_flags,
-		       struct dm_ioctl **param, int *param_flags)
+		       int ioctl_flags, struct dm_ioctl **param, int *param_flags)
 {
 	struct dm_ioctl *dmi;
 	int secure_data;
@@ -1734,18 +1733,13 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 		return -ENOMEM;
 	}
 
-	if (copy_from_user(dmi, user, param_kernel->data_size))
-		goto bad;
+	/* Copy from param_kernel (which was already copied from user) */
+	memcpy(dmi, param_kernel, minimum_data_size);
 
+	if (copy_from_user(&dmi->data, (char __user *)user + minimum_data_size,
+			   param_kernel->data_size - minimum_data_size))
+		goto bad;
 data_copied:
-	/*
-	 * Abort if something changed the ioctl data while it was being copied.
-	 */
-	if (dmi->data_size != param_kernel->data_size) {
-		DMERR("rejecting ioctl: data size modified while processing parameters");
-		goto bad;
-	}
-
 	/* Wipe the user buffer so we do not return it to userspace */
 	if (secure_data && clear_user(user, param_kernel->data_size))
 		goto bad;