net, ipv6: convert ifacaddr6.aca_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/if_inet6.h b/include/net/if_inet6.h
index 4bb52ce634e852b1fae7b534a1033ef7d96328ec..d4088d1a688d49fd3bb5ed3791c7755fd75c6ffe 100644 (file)
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -147,7 +147,7 @@ struct ifacaddr6 {
        struct rt6_info         *aca_rt;
        struct ifacaddr6        *aca_next;
        int                     aca_users;
-       atomic_t                aca_refcnt;
+       refcount_t              aca_refcnt;
        unsigned long           aca_cstamp;
        unsigned long           aca_tstamp;
 };

diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 514ac259f5433a43fc3cbfcaeb45847122594e79..0bbab8a4b5d846fa8c528dd4065383d770b85549 100644 (file)
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -203,12 +203,12 @@ void ipv6_sock_ac_close(struct sock *sk)
 
 static void aca_get(struct ifacaddr6 *aca)
 {
-       atomic_inc(&aca->aca_refcnt);
+       refcount_inc(&aca->aca_refcnt);
 }
 
 static void aca_put(struct ifacaddr6 *ac)
 {
-       if (atomic_dec_and_test(&ac->aca_refcnt)) {
+       if (refcount_dec_and_test(&ac->aca_refcnt)) {
                in6_dev_put(ac->aca_idev);
                dst_release(&ac->aca_rt->dst);
                kfree(ac);
@@ -232,7 +232,7 @@ static struct ifacaddr6 *aca_alloc(struct rt6_info *rt,
        aca->aca_users = 1;
        /* aca_tstamp should be updated upon changes */
        aca->aca_cstamp = aca->aca_tstamp = jiffies;
-       atomic_set(&aca->aca_refcnt, 1);
+       refcount_set(&aca->aca_refcnt, 1);
 
        return aca;
 }