net, llc: convert llc_sap.refcnt 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 <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>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/llc.h b/include/net/llc.h
index e8e61d4..dc35f25 100644 (file)
--- a/include/net/llc.h
+++ b/include/net/llc.h
@@ -55,7 +55,7 @@ struct llc_sap {
        unsigned char    state;
        unsigned char    p_bit;
        unsigned char    f_bit;
-       atomic_t         refcnt;
+       refcount_t               refcnt;
        int              (*rcv_func)(struct sk_buff *skb,
                                     struct net_device *dev,
                                     struct packet_type *pt,
@@ -113,14 +113,14 @@ struct llc_sap *llc_sap_open(unsigned char lsap,
                                        struct net_device *orig_dev));
 static inline void llc_sap_hold(struct llc_sap *sap)
 {
-       atomic_inc(&sap->refcnt);
+       refcount_inc(&sap->refcnt);
 }
 
 void llc_sap_close(struct llc_sap *sap);
 
 static inline void llc_sap_put(struct llc_sap *sap)
 {
-       if (atomic_dec_and_test(&sap->refcnt))
+       if (refcount_dec_and_test(&sap->refcnt))
                llc_sap_close(sap);
 }
 

diff --git a/net/llc/llc_core.c b/net/llc/llc_core.c
index 842851c..8904126 100644 (file)
--- a/net/llc/llc_core.c
+++ b/net/llc/llc_core.c
@@ -41,7 +41,7 @@ static struct llc_sap *llc_sap_alloc(void)
                spin_lock_init(&sap->sk_lock);
                for (i = 0; i < LLC_SK_LADDR_HASH_ENTRIES; i++)
                        INIT_HLIST_NULLS_HEAD(&sap->sk_laddr_hash[i], i);
-               atomic_set(&sap->refcnt, 1);
+               refcount_set(&sap->refcnt, 1);
        }
        return sap;
 }