net, ipv6: convert inet6_dev.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/addrconf.h b/include/net/addrconf.h
index d0889cb501726685e56a2d6cf333ab55c2d0d48a..620bd9a83ba9ef018c799f75d0febabd15e624ef 100644 (file)
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -316,7 +316,7 @@ static inline struct inet6_dev *in6_dev_get(const struct net_device *dev)
        rcu_read_lock();
        idev = rcu_dereference(dev->ip6_ptr);
        if (idev)
-               atomic_inc(&idev->refcnt);
+               refcount_inc(&idev->refcnt);
        rcu_read_unlock();
        return idev;
 }
@@ -332,18 +332,18 @@ void in6_dev_finish_destroy(struct inet6_dev *idev);
 
 static inline void in6_dev_put(struct inet6_dev *idev)
 {
-       if (atomic_dec_and_test(&idev->refcnt))
+       if (refcount_dec_and_test(&idev->refcnt))
                in6_dev_finish_destroy(idev);
 }
 
 static inline void __in6_dev_put(struct inet6_dev *idev)
 {
-       atomic_dec(&idev->refcnt);
+       refcount_dec(&idev->refcnt);
 }
 
 static inline void in6_dev_hold(struct inet6_dev *idev)
 {
-       atomic_inc(&idev->refcnt);
+       refcount_inc(&idev->refcnt);
 }
 
 void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp);

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index f656f9051acafa8026d391f32b026562e24d8c4e..e7a17b231afc34775f936971ff80e934572eaac2 100644 (file)
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -17,6 +17,7 @@
 
 #include <net/snmp.h>
 #include <linux/ipv6.h>
+#include <linux/refcount.h>
 
 /* inet6_dev.if_flags */
 
@@ -187,7 +188,7 @@ struct inet6_dev {
 
        struct ifacaddr6        *ac_list;
        rwlock_t                lock;
-       atomic_t                refcnt;
+       refcount_t              refcnt;
        __u32                   if_flags;
        int                     dead;
 

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 114fb64cf176c2c148d53c67c6dafa7891ae84aa..2365f1224c6b7b04a129cd33afa960b98ee316fc 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -426,7 +426,7 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
        }
 
        /* One reference from device. */
-       in6_dev_hold(ndev);
+       refcount_set(&ndev->refcnt, 1);
 
        if (dev->flags & (IFF_NOARP | IFF_LOOPBACK))
                ndev->cnf.accept_dad = -1;