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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: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Elena Reshetova 2017-03-17 14:10:27 +02:00 committed by Ilya Dryomov
parent 805692d0e0
commit 06dfa96399
2 changed files with 5 additions and 4 deletions
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3
include/linux/ceph/libceph.h
View File

@ -14,6 +14,7 @@
#include <linux/wait.h> #include <linux/wait.h>
#include <linux/writeback.h> #include <linux/writeback.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/refcount.h>
#include <linux/ceph/types.h> #include <linux/ceph/types.h>
#include <linux/ceph/messenger.h> #include <linux/ceph/messenger.h>
@ -161,7 +162,7 @@ struct ceph_client {
* dirtied. * dirtied.
*/ */
struct ceph_snap_context { struct ceph_snap_context {
atomic_t nref; refcount_t nref;
u64 seq; u64 seq;
u32 num_snaps; u32 num_snaps;
u64 snaps[]; u64 snaps[];

6
net/ceph/snapshot.c
View File

@ -49,7 +49,7 @@ struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
if (!snapc) if (!snapc)
return NULL; return NULL;
atomic_set(&snapc->nref, 1); refcount_set(&snapc->nref, 1);
snapc->num_snaps = snap_count; snapc->num_snaps = snap_count;
return snapc; 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) struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
{ {
if (sc) if (sc)
atomic_inc(&sc->nref); refcount_inc(&sc->nref);
return sc; return sc;
} }
EXPORT_SYMBOL(ceph_get_snap_context); EXPORT_SYMBOL(ceph_get_snap_context);
@ -68,7 +68,7 @@ void ceph_put_snap_context(struct ceph_snap_context *sc)
{ {
if (!sc) if (!sc)
return; return;
if (atomic_dec_and_test(&sc->nref)) { if (refcount_dec_and_test(&sc->nref)) {
/*printk(" deleting snap_context %p\n", sc);*/ /*printk(" deleting snap_context %p\n", sc);*/
kfree(sc); kfree(sc);
} }