From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f171.google.com ([209.85.212.171]:38584 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058AbbKAMpI (ORCPT ); Sun, 1 Nov 2015 07:45:08 -0500 Received: by wicll6 with SMTP id ll6so34863037wic.1 for ; Sun, 01 Nov 2015 04:45:07 -0800 (PST) From: Ilya Dryomov To: Greg KH Cc: stable@vger.kernel.org Subject: [PATCH] rbd: don't leak parent_spec in rbd_dev_probe_parent() Date: Sun, 1 Nov 2015 15:05:23 +0100 Message-Id: <1446386726-20335-2-git-send-email-idryomov@gmail.com> In-Reply-To: <1446386726-20335-1-git-send-email-idryomov@gmail.com> References: <1446386726-20335-1-git-send-email-idryomov@gmail.com> Sender: stable-owner@vger.kernel.org List-ID: Currently we leak parent_spec and trigger a "parent reference underflow" warning if rbd_dev_create() in rbd_dev_probe_parent() fails. The problem is we take the !parent out_err branch and that only drops refcounts; parent_spec that would've been freed had we called rbd_dev_unparent() remains and triggers rbd_warn() in rbd_dev_parent_put() - at that point we have parent_spec != NULL and parent_ref == 0, so counter ends up being -1 after the decrement. Redo rbd_dev_probe_parent() to fix this. Cc: stable@vger.kernel.org # 3.10+, needs backporting for < 4.2 Signed-off-by: Ilya Dryomov Reviewed-by: Alex Elder [idryomov@gmail.com: backport to < 4.2: rbd_dev->opts] --- drivers/block/rbd.c | 35 +++++++++++++++-------------------- 1 file changed, 15 insertions(+), 20 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index fe8f1e4b4c7c..5f9b8e93906b 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -5145,41 +5145,36 @@ out_err: static int rbd_dev_probe_parent(struct rbd_device *rbd_dev) { struct rbd_device *parent = NULL; - struct rbd_spec *parent_spec; - struct rbd_client *rbdc; int ret; if (!rbd_dev->parent_spec) return 0; - /* - * We need to pass a reference to the client and the parent - * spec when creating the parent rbd_dev. Images related by - * parent/child relationships always share both. - */ - parent_spec = rbd_spec_get(rbd_dev->parent_spec); - rbdc = __rbd_get_client(rbd_dev->rbd_client); - ret = -ENOMEM; - parent = rbd_dev_create(rbdc, parent_spec); - if (!parent) + parent = rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec); + if (!parent) { + ret = -ENOMEM; goto out_err; + } + + /* + * Images related by parent/child relationships always share + * rbd_client and spec/parent_spec, so bump their refcounts. + */ + __rbd_get_client(rbd_dev->rbd_client); + rbd_spec_get(rbd_dev->parent_spec); ret = rbd_dev_image_probe(parent, false); if (ret < 0) goto out_err; + rbd_dev->parent = parent; atomic_set(&rbd_dev->parent_ref, 1); - return 0; + out_err: - if (parent) { - rbd_dev_unparent(rbd_dev); + rbd_dev_unparent(rbd_dev); + if (parent) rbd_dev_destroy(parent); - } else { - rbd_put_client(rbdc); - rbd_spec_put(parent_spec); - } - return ret; } -- 2.4.3