[PATCH 11/23] net, x25: convert x25_route.refcnt from atomic_t to refcount_t

[Elena Reshetova]

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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 include/net/x25.h   | 7 ++++---
 net/x25/x25_route.c | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/net/x25.h b/include/net/x25.h
index c383aa4..83a6d31 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -11,6 +11,7 @@
 #define _X25_H 
 #include <linux/x25.h>
 #include <linux/slab.h>
+#include <linux/refcount.h>
 #include <net/sock.h>
 
 #define        X25_ADDR_LEN                    16
@@ -129,7 +130,7 @@ struct x25_route {
        struct x25_address      address;
        unsigned int            sigdigits;
        struct net_device       *dev;
-       atomic_t                refcnt;
+       refcount_t              refcnt;
 };
 
 struct x25_neigh {
@@ -265,12 +266,12 @@ void x25_route_free(void);
 
 static __inline__ void x25_route_hold(struct x25_route *rt)
 {
-       atomic_inc(&rt->refcnt);
+       refcount_inc(&rt->refcnt);
 }
 
 static __inline__ void x25_route_put(struct x25_route *rt)
 {
-       if (atomic_dec_and_test(&rt->refcnt))
+       if (refcount_dec_and_test(&rt->refcnt))
                kfree(rt);
 }
 
diff --git a/net/x25/x25_route.c b/net/x25/x25_route.c
index 277c8d2..b85b889 100644
--- a/net/x25/x25_route.c
+++ b/net/x25/x25_route.c
@@ -55,7 +55,7 @@ static int x25_add_route(struct x25_address *address, 
unsigned int sigdigits,
 
        rt->sigdigits = sigdigits;
        rt->dev       = dev;
-       atomic_set(&rt->refcnt, 1);
+       refcount_set(&rt->refcnt, 1);
 
        list_add(&rt->node, &x25_route_list);
        rc = 0;
-- 
2.7.4