[PATCH 26/36] net, xfrm: convert xfrm_state.refcnt from atomic_t to refcount_t

From: Elena Reshetova
Date: Tue Jul 04 2017 - 09:02:34 EST


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/net/xfrm.h | 9 +++++----
net/xfrm/xfrm_state.c | 4 ++--
2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 01fa357..f5272a2 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -13,6 +13,7 @@
#include <linux/mutex.h>
#include <linux/audit.h>
#include <linux/slab.h>
+#include <linux/refcount.h>

#include <net/sock.h>
#include <net/dst.h>
@@ -137,7 +138,7 @@ struct xfrm_state {
struct hlist_node bysrc;
struct hlist_node byspi;

- atomic_t refcnt;
+ refcount_t refcnt;
spinlock_t lock;

struct xfrm_id id;
@@ -837,18 +838,18 @@ void __xfrm_state_destroy(struct xfrm_state *);

static inline void __xfrm_state_put(struct xfrm_state *x)
{
- atomic_dec(&x->refcnt);
+ refcount_dec(&x->refcnt);
}

static inline void xfrm_state_put(struct xfrm_state *x)
{
- if (atomic_dec_and_test(&x->refcnt))
+ if (refcount_dec_and_test(&x->refcnt))
__xfrm_state_destroy(x);
}

static inline void xfrm_state_hold(struct xfrm_state *x)
{
- atomic_inc(&x->refcnt);
+ refcount_inc(&x->refcnt);
}

static inline bool addr_match(const void *token1, const void *token2,
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 4a28f66..6c0956d 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -48,7 +48,7 @@ static HLIST_HEAD(xfrm_state_gc_list);

static inline bool xfrm_state_hold_rcu(struct xfrm_state __rcu *x)
{
- return atomic_inc_not_zero(&x->refcnt);
+ return refcount_inc_not_zero(&x->refcnt);
}

static inline unsigned int xfrm_dst_hash(struct net *net,
@@ -558,7 +558,7 @@ struct xfrm_state *xfrm_state_alloc(struct net *net)

if (x) {
write_pnet(&x->xs_net, net);
- atomic_set(&x->refcnt, 1);
+ refcount_set(&x->refcnt, 1);
atomic_set(&x->tunnel_users, 0);
INIT_LIST_HEAD(&x->km.all);
INIT_HLIST_NODE(&x->bydst);
--
2.7.4