net: convert sock.sk_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.

This patch uses refcount_inc_not_zero() instead of
atomic_inc_not_zero_hint() due to absense of a _hint()
version of refcount API. If the hint() version must
be used, we might need to revisit API.

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>

2 files changed, 2 insertions, 2 deletions

diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index 8a8f77a247e6..91e3ba280706 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -657,7 +657,7 @@ static int bt_seq_show(struct seq_file *seq, void *v)
                 seq_printf(seq,
                            "%pK %-6d %-6u %-6u %-6u %-6lu %-6lu",
                            sk,
-                           atomic_read(&sk->sk_refcnt),
+                           refcount_read(&sk->sk_refcnt),
                            sk_rmem_alloc_get(sk),
                            sk_wmem_alloc_get(sk),
                            from_kuid(seq_user_ns(seq), sock_i_uid(sk)),
diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index ac3c650cb234..2172ae509cf1 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -197,7 +197,7 @@ static void rfcomm_sock_kill(struct sock *sk)
         if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
                 return;
 
-        BT_DBG("sk %p state %d refcnt %d", sk, sk->sk_state, atomic_read(&sk->sk_refcnt));
+        BT_DBG("sk %p state %d refcnt %d", sk, sk->sk_state, refcount_read(&sk->sk_refcnt));
 
         /* Kill poor orphan */
         bt_sock_unlink(&rfcomm_sk_list, sk);