net: convert netpoll_info.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/linux/netpoll.h b/include/linux/netpoll.h
index 1828900..27c0aaa 100644 (file)
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -11,6 +11,7 @@
 #include <linux/interrupt.h>
 #include <linux/rcupdate.h>
 #include <linux/list.h>
+#include <linux/refcount.h>
 
 union inet_addr {
        __u32           all[4];
@@ -34,7 +35,7 @@ struct netpoll {
 };
 
 struct netpoll_info {
-       atomic_t refcnt;
+       refcount_t refcnt;
 
        struct semaphore dev_lock;
 

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index a835155..d3408a6 100644 (file)
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -632,7 +632,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
                skb_queue_head_init(&npinfo->txq);
                INIT_DELAYED_WORK(&npinfo->tx_work, queue_process);
 
-               atomic_set(&npinfo->refcnt, 1);
+               refcount_set(&npinfo->refcnt, 1);
 
                ops = np->dev->netdev_ops;
                if (ops->ndo_netpoll_setup) {
@@ -642,7 +642,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev)
                }
        } else {
                npinfo = rtnl_dereference(ndev->npinfo);
-               atomic_inc(&npinfo->refcnt);
+               refcount_inc(&npinfo->refcnt);
        }
 
        npinfo->netpoll = np;
@@ -821,7 +821,7 @@ void __netpoll_cleanup(struct netpoll *np)
 
        synchronize_srcu(&netpoll_srcu);
 
-       if (atomic_dec_and_test(&npinfo->refcnt)) {
+       if (refcount_dec_and_test(&npinfo->refcnt)) {
                const struct net_device_ops *ops;
 
                ops = np->dev->netdev_ops;