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Subject[PATCH 24/36] net, x25: convert x25_route.refcnt from atomic_t to refcount_t
Date
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>
---
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 6d30a01..1ac1400 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
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