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From:   Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
To:     marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com,
        davem@davemloft.net, kuba@kernel.org, sudipm.mukherjee@gmail.com
Cc:     Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>,
        linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, skhan@linuxfoundation.org,
        gregkh@linuxfoundation.org,
        linux-kernel-mentees@lists.linuxfoundation.org
Subject: [PATCH v6 4/6] Bluetooth: serialize calls to sco_sock_{set,clear}_timer
Date:   Tue, 10 Aug 2021 12:14:08 +0800
Message-Id: <20210810041410.142035-5-desmondcheongzx@gmail.com>
In-Reply-To: <20210810041410.142035-1-desmondcheongzx@gmail.com>
References: <20210810041410.142035-1-desmondcheongzx@gmail.com>
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Currently, calls to sco_sock_set_timer are made under the locked
socket, but this does not apply to all calls to sco_sock_clear_timer.

Both sco_sock_{set,clear}_timer should be serialized by lock_sock to
prevent unexpected concurrent clearing/setting of timers.

Additionally, since sco_pi(sk)->conn is only cleared under the locked
socket, this change allows us to avoid races between
sco_sock_clear_timer and the call to kfree(conn) in sco_conn_del.

Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
---
 net/bluetooth/sco.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 68b51e321e82..77490338f4fa 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -453,8 +453,8 @@ static void __sco_sock_close(struct sock *sk)
 /* Must be called on unlocked socket. */
 static void sco_sock_close(struct sock *sk)
 {
-	sco_sock_clear_timer(sk);
 	lock_sock(sk);
+	sco_sock_clear_timer(sk);
 	__sco_sock_close(sk);
 	release_sock(sk);
 	sco_sock_kill(sk);
@@ -1104,8 +1104,8 @@ static void sco_conn_ready(struct sco_conn *conn)
 	BT_DBG("conn %p", conn);
 
 	if (sk) {
-		sco_sock_clear_timer(sk);
 		lock_sock(sk);
+		sco_sock_clear_timer(sk);
 		sk->sk_state = BT_CONNECTED;
 		sk->sk_state_change(sk);
 		release_sock(sk);
-- 
2.25.1