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Commit 06dfa963 authored by Elena Reshetova's avatar Elena Reshetova Committed by Ilya Dryomov
Browse files

libceph: convert ceph_snap_context.nref from atomic_t to refcount_t 



refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 805692d0

include/linux/ceph/libceph.h

+2 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/wait.h>

#include <linux/writeback.h>

#include <linux/slab.h>

#include <linux/refcount.h>



#include <linux/ceph/types.h>

#include <linux/ceph/messenger.h>
@@ -161,7 +162,7 @@ struct ceph_client { 
 * dirtied.

 */

struct ceph_snap_context {

	atomic_t nref;

	refcount_t nref;

	u64 seq;

	u32 num_snaps;

	u64 snaps[];

net/ceph/snapshot.c

+3 −3
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ struct ceph_snap_context *ceph_create_snap_context(u32 snap_count, 
	if (!snapc)

		return NULL;



	atomic_set(&snapc->nref, 1);

	refcount_set(&snapc->nref, 1);

	snapc->num_snaps = snap_count;



	return snapc;
@@ -59,7 +59,7 @@ EXPORT_SYMBOL(ceph_create_snap_context); 
struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)

{

	if (sc)

		atomic_inc(&sc->nref);

		refcount_inc(&sc->nref);

	return sc;

}

EXPORT_SYMBOL(ceph_get_snap_context);
@@ -68,7 +68,7 @@ void ceph_put_snap_context(struct ceph_snap_context *sc) 
{

	if (!sc)

		return;

	if (atomic_dec_and_test(&sc->nref)) {

	if (refcount_dec_and_test(&sc->nref)) {

		/*printk(" deleting snap_context %p\n", sc);*/

		kfree(sc);

	}