net, ax25: convert ax25_cb.refcount from atomic_t to refcount_t

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 <[email protected]> Signed-off-by: Hans Liljestrand <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: David Windsor <[email protected]> Signed-off-by: David S. Miller <[email protected]>
mrcsosa · Jul 4, 2017 · b6d52ed · b6d52ed
1 parent 39f25d4
commit b6d52ed
Show file tree

Hide file tree

Showing 2 changed files with 4 additions and 4 deletions.
diff --git a/include/net/ax25.h b/include/net/ax25.h
@@ -244,7 +244,7 @@ typedef struct ax25_cb {
 	unsigned char		window;
 	struct timer_list	timer, dtimer;
 	struct sock		*sk;		/* Backlink to socket */
-	atomic_t		refcount;
+	refcount_t		refcount;
 } ax25_cb;
 
 struct ax25_sock {
@@ -266,11 +266,11 @@ static inline struct ax25_cb *sk_to_ax25(const struct sock *sk)
 	hlist_for_each_entry(__ax25, list, ax25_node)
 
 #define ax25_cb_hold(__ax25) \
-	atomic_inc(&((__ax25)->refcount))
+	refcount_inc(&((__ax25)->refcount))
 
 static __inline__ void ax25_cb_put(ax25_cb *ax25)
 {
-	if (atomic_dec_and_test(&ax25->refcount)) {
+	if (refcount_dec_and_test(&ax25->refcount)) {
 		kfree(ax25->digipeat);
 		kfree(ax25);
 	}

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
@@ -510,7 +510,7 @@ ax25_cb *ax25_create_cb(void)
 	if ((ax25 = kzalloc(sizeof(*ax25), GFP_ATOMIC)) == NULL)
 		return NULL;
 
-	atomic_set(&ax25->refcount, 1);
+	refcount_set(&ax25->refcount, 1);
 
 	skb_queue_head_init(&ax25->write_queue);
 	skb_queue_head_init(&ax25->frag_queue);