From 1f2c6651f69c14d0d3a9cfbda44ea101b02160ba Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Sun, 11 Oct 2015 19:38:00 +0200 Subject: rbd: don't leak parent_spec in rbd_dev_probe_parent() 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 --- drivers/block/rbd.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-) (limited to 'drivers/block/rbd.c') diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index f5e49b639818..028db28cb8a0 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -5134,41 +5134,37 @@ 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, NULL); - if (!parent) + parent = rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec, + NULL); + 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; } -- cgit v1.2.3-55-g7522