From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162166AbbKFTmU (ORCPT ); Fri, 6 Nov 2015 14:42:20 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:48172 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162025AbbKFTmN (ORCPT ); Fri, 6 Nov 2015 14:42:13 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ilya Dryomov , Josh Durgin Subject: [PATCH 3.10 12/24] rbd: prevent kernel stack blow up on rbd map Date: Fri, 6 Nov 2015 11:24:50 -0800 Message-Id: <20151106192413.291680510@linuxfoundation.org> X-Mailer: git-send-email 2.6.2 In-Reply-To: <20151106192412.414671726@linuxfoundation.org> References: <20151106192412.414671726@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilya Dryomov commit 6d69bb536bac0d403d83db1ca841444981b280cd upstream. Mapping an image with a long parent chain (e.g. image foo, whose parent is bar, whose parent is baz, etc) currently leads to a kernel stack overflow, due to the following recursion in the reply path: rbd_osd_req_callback() rbd_obj_request_complete() rbd_img_obj_callback() rbd_img_parent_read_callback() rbd_obj_request_complete() ... Limit the parent chain to 16 images, which is ~5K worth of stack. When the above recursion is eliminated, this limit can be lifted. Fixes: http://tracker.ceph.com/issues/12538 Signed-off-by: Ilya Dryomov Reviewed-by: Josh Durgin [idryomov@gmail.com: backport to 3.10: rbd_dev->opts, context] Signed-off-by: Greg Kroah-Hartman --- drivers/block/rbd.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -93,6 +93,8 @@ static int atomic_dec_return_safe(atomic #define RBD_MINORS_PER_MAJOR 256 /* max minors per blkdev */ +#define RBD_MAX_PARENT_CHAIN_LEN 16 + #define RBD_SNAP_DEV_NAME_PREFIX "snap_" #define RBD_MAX_SNAP_NAME_LEN \ (NAME_MAX - (sizeof (RBD_SNAP_DEV_NAME_PREFIX) - 1)) @@ -394,7 +396,7 @@ static ssize_t rbd_add(struct bus_type * size_t count); static ssize_t rbd_remove(struct bus_type *bus, const char *buf, size_t count); -static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping); +static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth); static void rbd_spec_put(struct rbd_spec *spec); static struct bus_attribute rbd_bus_attrs[] = { @@ -4831,7 +4833,12 @@ out_err: return ret; } -static int rbd_dev_probe_parent(struct rbd_device *rbd_dev) +/* + * @depth is rbd_dev_image_probe() -> rbd_dev_probe_parent() -> + * rbd_dev_image_probe() recursion depth, which means it's also the + * length of the already discovered part of the parent chain. + */ +static int rbd_dev_probe_parent(struct rbd_device *rbd_dev, int depth) { struct rbd_device *parent = NULL; int ret; @@ -4839,6 +4846,12 @@ static int rbd_dev_probe_parent(struct r if (!rbd_dev->parent_spec) return 0; + if (++depth > RBD_MAX_PARENT_CHAIN_LEN) { + pr_info("parent chain is too long (%d)\n", depth); + ret = -EINVAL; + goto out_err; + } + parent = rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec); if (!parent) { ret = -ENOMEM; @@ -4852,7 +4865,7 @@ static int rbd_dev_probe_parent(struct r __rbd_get_client(rbd_dev->rbd_client); rbd_spec_get(rbd_dev->parent_spec); - ret = rbd_dev_image_probe(parent, false); + ret = rbd_dev_image_probe(parent, depth); if (ret < 0) goto out_err; @@ -4969,7 +4982,7 @@ static void rbd_dev_image_release(struct * parent), initiate a watch on its header object before using that * object to get detailed information about the rbd image. */ -static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping) +static int rbd_dev_image_probe(struct rbd_device *rbd_dev, int depth) { int ret; int tmp; @@ -4990,7 +5003,7 @@ static int rbd_dev_image_probe(struct rb if (ret) goto err_out_format; - if (mapping) { + if (!depth) { ret = rbd_dev_header_watch_sync(rbd_dev, true); if (ret) goto out_header_name; @@ -5007,7 +5020,7 @@ static int rbd_dev_image_probe(struct rb if (ret) goto err_out_probe; - ret = rbd_dev_probe_parent(rbd_dev); + ret = rbd_dev_probe_parent(rbd_dev, depth); if (ret) goto err_out_probe; @@ -5018,7 +5031,7 @@ static int rbd_dev_image_probe(struct rb err_out_probe: rbd_dev_unprobe(rbd_dev); err_out_watch: - if (mapping) { + if (!depth) { tmp = rbd_dev_header_watch_sync(rbd_dev, false); if (tmp) rbd_warn(rbd_dev, "unable to tear down " @@ -5089,7 +5102,7 @@ static ssize_t rbd_add(struct bus_type * rbdc = NULL; /* rbd_dev now owns this */ spec = NULL; /* rbd_dev now owns this */ - rc = rbd_dev_image_probe(rbd_dev, true); + rc = rbd_dev_image_probe(rbd_dev, 0); if (rc < 0) goto err_out_rbd_dev;