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Subject[PATCH 11/17] net: convert netpoll_info.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/linux/netpoll.h | 3 ++-
net/core/netpoll.c | 6 +++---
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index 1828900..27c0aaa 100644
--- 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
--- 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;
--
2.7.4
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