linux-kernel - [PATCH] Bluetooth: SCO: fix ABBA deadlock in sco_connect

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Message-ID: <20250222114809.11634-1-aha310510@gmail.com>
Date: Sat, 22 Feb 2025 20:48:09 +0900
From: Jeongjun Park <aha310510@...il.com>
To: marcel@...tmann.org,
	johan.hedberg@...il.com,
	luiz.dentz@...il.com
Cc: gustavo.padovan@...labora.co.uk,
	andre.guedes@...nbossa.org,
	linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Jeongjun Park <aha310510@...il.com>
Subject: [PATCH] Bluetooth: SCO: fix ABBA deadlock in sco_connect_cfm

Caused by previous commit 405280887f8f causes ABBA deadlock. So we need to 
change the lock order to prevent deadlock.

Fixes: 405280887f8f ("Bluetooth: Reduce critical section in sco_conn_ready")
Signed-off-by: Jeongjun Park <aha310510@...il.com>
---
 net/bluetooth/sco.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index aa7bfe26cb40..8f1377f4a27c 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -289,13 +289,11 @@ static int sco_chan_add(struct sco_conn *conn, struct sock *sk,
 {
 	int err = 0;
 
-	sco_conn_lock(conn);
 	if (conn->sk)
 		err = -EBUSY;
 	else
 		__sco_chan_add(conn, sk, parent);
 
-	sco_conn_unlock(conn);
 	return err;
 }
 
@@ -343,11 +341,13 @@ static int sco_connect(struct sock *sk)
 		goto unlock;
 	}
 
+	sco_conn_lock(conn);
 	lock_sock(sk);
 
 	err = sco_chan_add(conn, sk, NULL);
 	if (err) {
 		release_sock(sk);
+		sco_conn_unlock(conn);
 		goto unlock;
 	}
 
@@ -363,6 +363,7 @@ static int sco_connect(struct sock *sk)
 	}
 
 	release_sock(sk);
+	sco_conn_unlock(conn);
 
 unlock:
 	hci_dev_unlock(hdev);
--