linux-kernel - [PATCH AUTOSEL 4.19 7/9] Bluetooth: L2CAP: Fix use-after-free

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Message-Id: <20230724013445.2334326-7-sashal@kernel.org>
Date:   Sun, 23 Jul 2023 21:34:43 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zhengping Jiang <jiangzp@...gle.com>,
        Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>, marcel@...tmann.org,
        gustavo@...ovan.org, johan.hedberg@...il.com, davem@...emloft.net,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 7/9] Bluetooth: L2CAP: Fix use-after-free

From: Zhengping Jiang <jiangzp@...gle.com>

[ Upstream commit f752a0b334bb95fe9b42ecb511e0864e2768046f ]

Fix potential use-after-free in l2cap_le_command_rej.

Signed-off-by: Zhengping Jiang <jiangzp@...gle.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/bluetooth/l2cap_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index fcc471f921895..9346fae5d664b 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -5705,9 +5705,14 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn,
 	if (!chan)
 		goto done;
 
+	chan = l2cap_chan_hold_unless_zero(chan);
+	if (!chan)
+		goto done;
+
 	l2cap_chan_lock(chan);
 	l2cap_chan_del(chan, ECONNREFUSED);
 	l2cap_chan_unlock(chan);
+	l2cap_chan_put(chan);
 
 done:
 	mutex_unlock(&conn->chan_lock);
-- 
2.39.2