On Fri, Mar 17, 2017 at 1:10 PM, Elena Reshetova
<elena.reshetova@xxxxxxxxx> wrote:
> 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@xxxxxxxxx>
> Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
> ---
> include/linux/ceph/libceph.h | 3 ++-
> net/ceph/snapshot.c | 6 +++---
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
> index 1816c5e..26dc674 100644
> --- a/include/linux/ceph/libceph.h
> +++ b/include/linux/ceph/libceph.h
> @@ -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>
> @@ -159,7 +160,7 @@ struct ceph_client {
> * dirtied.
> */
> struct ceph_snap_context {
> - atomic_t nref;
> + refcount_t nref;
> u64 seq;
> u32 num_snaps;
> u64 snaps[];
> diff --git a/net/ceph/snapshot.c b/net/ceph/snapshot.c
> index 705414e..e14a5d0 100644
> --- a/net/ceph/snapshot.c
> +++ b/net/ceph/snapshot.c
> @@ -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);
> }
Applied.
Thanks,
Ilya
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