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/osd_client.h | 3 ++-
> net/ceph/osd_client.c | 16 ++++++++--------
> 2 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 2ea0c28..5ce0cd6 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -5,6 +5,7 @@
> #include <linux/kref.h>
> #include <linux/mempool.h>
> #include <linux/rbtree.h>
> +#include <linux/refcount.h>
>
> #include <linux/ceph/types.h>
> #include <linux/ceph/osdmap.h>
> @@ -27,7 +28,7 @@ typedef void (*ceph_osdc_callback_t)(struct ceph_osd_request *);
>
> /* a given osd we're communicating with */
> struct ceph_osd {
> - atomic_t o_ref;
> + refcount_t o_ref;
> struct ceph_osd_client *o_osdc;
> int o_osd;
> int o_incarnation;
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index b65bbf9..99a51f0 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -1005,7 +1005,7 @@ static bool osd_registered(struct ceph_osd *osd)
> */
> static void osd_init(struct ceph_osd *osd)
> {
> - atomic_set(&osd->o_ref, 1);
> + refcount_set(&osd->o_ref, 1);
> RB_CLEAR_NODE(&osd->o_node);
> osd->o_requests = RB_ROOT;
> osd->o_linger_requests = RB_ROOT;
> @@ -1050,9 +1050,9 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
>
> static struct ceph_osd *get_osd(struct ceph_osd *osd)
> {
> - if (atomic_inc_not_zero(&osd->o_ref)) {
> - dout("get_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref)-1,
> - atomic_read(&osd->o_ref));
> + if (refcount_inc_not_zero(&osd->o_ref)) {
> + dout("get_osd %p %d -> %d\n", osd, refcount_read(&osd->o_ref)-1,
> + refcount_read(&osd->o_ref));
> return osd;
> } else {
> dout("get_osd %p FAIL\n", osd);
> @@ -1062,9 +1062,9 @@ static struct ceph_osd *get_osd(struct ceph_osd *osd)
>
> static void put_osd(struct ceph_osd *osd)
> {
> - dout("put_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref),
> - atomic_read(&osd->o_ref) - 1);
> - if (atomic_dec_and_test(&osd->o_ref)) {
> + dout("put_osd %p %d -> %d\n", osd, refcount_read(&osd->o_ref),
> + refcount_read(&osd->o_ref) - 1);
> + if (refcount_dec_and_test(&osd->o_ref)) {
> osd_cleanup(osd);
> kfree(osd);
> }
> @@ -4092,7 +4092,7 @@ void ceph_osdc_stop(struct ceph_osd_client *osdc)
> close_osd(osd);
> }
> up_write(&osdc->lock);
> - WARN_ON(atomic_read(&osdc->homeless_osd.o_ref) != 1);
> + WARN_ON(refcount_read(&osdc->homeless_osd.o_ref) != 1);
> osd_cleanup(&osdc->homeless_osd);
>
> WARN_ON(!list_empty(&osdc->osd_lru));
Applied.
Thanks,
Ilya
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