net, sctp: convert sctp_transport.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/sctp/structs.h b/include/net/sctp/structs.h
index 0dfc5c14b6965b67c320218e174b2d8790b7d8ed..6a0d372585064ada2fab4597d799f0d94161ec88 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -735,7 +735,7 @@ struct sctp_transport {
        struct rhlist_head node;
 
        /* Reference counting. */
-       atomic_t refcnt;
+       refcount_t refcnt;
                /* RTO-Pending : A flag used to track if one of the DATA
                 *              chunks sent to this address is currently being
                 *              used to compute a RTT. If this flag is 0,

diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 7cdd6bcddbc5ad277f525635cf56788f70a4ee30..80a97c8501a77be978a01ae9ec769f4c365bc14f 100644 (file)
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -99,7 +99,7 @@ static struct sctp_transport *sctp_transport_init(struct net *net,
        /* Initialize the 64-bit random nonce sent with heartbeat. */
        get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));
 
-       atomic_set(&peer->refcnt, 1);
+       refcount_set(&peer->refcnt, 1);
 
        return peer;
 }
@@ -172,7 +172,7 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
  */
 static void sctp_transport_destroy(struct sctp_transport *transport)
 {
-       if (unlikely(atomic_read(&transport->refcnt))) {
+       if (unlikely(refcount_read(&transport->refcnt))) {
                WARN(1, "Attempt to destroy undead transport %p!\n", transport);
                return;
        }
@@ -311,7 +311,7 @@ void sctp_transport_route(struct sctp_transport *transport,
 /* Hold a reference to a transport.  */
 int sctp_transport_hold(struct sctp_transport *transport)
 {
-       return atomic_add_unless(&transport->refcnt, 1, 0);
+       return refcount_inc_not_zero(&transport->refcnt);
 }
 
 /* Release a reference to a transport and clean up
@@ -319,7 +319,7 @@ int sctp_transport_hold(struct sctp_transport *transport)
  */
 void sctp_transport_put(struct sctp_transport *transport)
 {
-       if (atomic_dec_and_test(&transport->refcnt))
+       if (refcount_dec_and_test(&transport->refcnt))
                sctp_transport_destroy(transport);
 }