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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

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Pull Ceph fixes from Sage Weil:
 "Two fixes.

  One is a stopgap to prevent a stack blowout when users have a deep
  chain of image clones.  (We'll rewrite this code to be non-recursive
  for the next window, but in the meantime this is a simple fix that
  avoids a crash.)

  The second fixes a refcount underflow"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  rbd: prevent kernel stack blow up on rbd map
  rbd: don't leak parent_spec in rbd_dev_probe_parent()
This commit is contained in:
Linus Torvalds 2015-10-24 07:19:33 +09:00
commit ef594c421a
1 changed files with 45 additions and 36 deletions
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81
drivers/block/rbd.c
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@ -96,6 +96,8 @@ static int atomic_dec_return_safe(atomic_t *v)
#define RBD_MINORS_PER_MAJOR 256
#define RBD_SINGLE_MAJOR_PART_SHIFT 4
#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))
@ -426,7 +428,7 @@ static ssize_t rbd_add_single_major(struct bus_type *bus, const char *buf,
size_t count);
static ssize_t rbd_remove_single_major(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 int rbd_dev_id_to_minor(int dev_id)
@ -5131,44 +5133,51 @@ static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
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;
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)
if (++depth > RBD_MAX_PARENT_CHAIN_LEN) {
pr_info("parent chain is too long (%d)\n", depth);
ret = -EINVAL;
goto out_err;
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_destroy(parent);
} else {
rbd_put_client(rbdc);
rbd_spec_put(parent_spec);
}
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, depth);
if (ret < 0)
goto out_err;
rbd_dev->parent = parent;
atomic_set(&rbd_dev->parent_ref, 1);
return 0;
out_err:
rbd_dev_unparent(rbd_dev);
if (parent)
rbd_dev_destroy(parent);
return ret;
}
@ -5286,7 +5295,7 @@ static void rbd_dev_image_release(struct rbd_device *rbd_dev)
* 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;
@ -5304,7 +5313,7 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)
if (ret)
goto err_out_format;
if (mapping) {
if (!depth) {
ret = rbd_dev_header_watch_sync(rbd_dev);
if (ret) {
if (ret == -ENOENT)
@ -5325,7 +5334,7 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)
* Otherwise this is a parent image, identified by pool, image
* and snap ids - need to fill in names for those ids.
*/
if (mapping)
if (!depth)
ret = rbd_spec_fill_snap_id(rbd_dev);
else
ret = rbd_spec_fill_names(rbd_dev);
@ -5347,12 +5356,12 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)
* Need to warn users if this image is the one being
* mapped and has a parent.
*/
if (mapping && rbd_dev->parent_spec)
if (!depth && rbd_dev->parent_spec)
rbd_warn(rbd_dev,
"WARNING: kernel layering is EXPERIMENTAL!");
}
ret = rbd_dev_probe_parent(rbd_dev);
ret = rbd_dev_probe_parent(rbd_dev, depth);
if (ret)
goto err_out_probe;
@ -5363,7 +5372,7 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping)
err_out_probe:
rbd_dev_unprobe(rbd_dev);
err_out_watch:
if (mapping)
if (!depth)
rbd_dev_header_unwatch_sync(rbd_dev);
out_header_name:
kfree(rbd_dev->header_name);
@ -5426,7 +5435,7 @@ static ssize_t do_rbd_add(struct bus_type *bus,
spec = NULL; /* rbd_dev now owns this */
rbd_opts = 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;