From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DFE1D43CEF9; Tue, 21 Jul 2026 21:58:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671089; cv=none; b=YSBYRAN2U4UMelcnc15Q48zY7n4M4CN8S1wNryQNAl+N5bKYGdKGtbsPWZH5mbRLi+3Mhy4g0k1AFxr1I2WQdXAfQvdOmClCwzezvDr0K0DauWSqCd8no3BeW9zGRL+v+KfkT5gKU3pTSIsAfXa+JdVYfE3D5DJf3g/JfIvZYTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671089; c=relaxed/simple; bh=U8I+qGFWmkJNQ5SBEe8Dybhfm4d+NXOBNLzXkJsbvus=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MxeKG+XJ70rPj0aIm0fVvgmzkFFTOtLA9XsuswPL2smHo/vZXT7ft1+91Y5s2p1hPVbVNzEpOQxYJBeVoitdsQNTehwGQ8wtafH7NXX0W9U4L81+cVzqo+0xYtnfFKLW34kXzGWlGQiVK89vLqGQBl5mUwvwGxJQZgRXpMjjuvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h4ysHH+O; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h4ysHH+O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BD291F000E9; Tue, 21 Jul 2026 21:58:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784671084; bh=FfaExltcBpfNOO+XCYAAyNSqb2gXk5hvl21NVG8hWKY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=h4ysHH+OltUHzy3DmHWlXcsl5TINbvxBVUwSUFVLYHONUJRrOLrrck0dfBx4m/aK+ N/rF2dw74iGQDmWVlAR8zv+7K9xnxm95cVMDCw69N1kxnI5JK6u/1hFAI4hcDR768H ToHhPmiG7fdjrB4JoS4WMAoBoGoLyEZ035TqGwwA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+fed5dce4553262f3b35c@syzkaller.appspotmail.com, Yousef Alhouseen , Luiz Augusto von Dentz Subject: [PATCH 5.15 112/843] Bluetooth: bnep: pin L2CAP connection during netdev registration Date: Tue, 21 Jul 2026 17:15:47 +0200 Message-ID: <20260721152408.522276768@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yousef Alhouseen commit bb067a99a0356196c0b89a95721985485ebce5a5 upstream. bnep_add_connection() reads the L2CAP connection without holding the channel lock, then passes its HCI device to register_netdev(). Controller teardown can clear and release that connection concurrently, leaving the network device registration path to dereference a freed parent device. Take a reference to the L2CAP connection while holding the channel lock. Retain it until register_netdev() has taken the parent device reference. Fixes: 65f53e9802db ("Bluetooth: Access BNEP session addresses through L2CAP channel") Reported-by: syzbot+fed5dce4553262f3b35c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=fed5dce4553262f3b35c Cc: stable@vger.kernel.org Signed-off-by: Yousef Alhouseen Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/bnep/core.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) --- a/net/bluetooth/bnep/core.c +++ b/net/bluetooth/bnep/core.c @@ -562,14 +562,18 @@ static int bnep_session(void *arg) return 0; } -static struct device *bnep_get_device(struct bnep_session *session) +static struct l2cap_conn *bnep_get_conn(struct bnep_session *session) { - struct l2cap_conn *conn = l2cap_pi(session->sock->sk)->chan->conn; + struct l2cap_chan *chan = l2cap_pi(session->sock->sk)->chan; + struct l2cap_conn *conn; - if (!conn || !conn->hcon) - return NULL; + l2cap_chan_lock(chan); + conn = chan->conn; + if (conn) + l2cap_conn_get(conn); + l2cap_chan_unlock(chan); - return &conn->hcon->dev; + return conn; } static struct device_type bnep_type = { @@ -581,6 +585,7 @@ int bnep_add_connection(struct bnep_conn u32 valid_flags = BIT(BNEP_SETUP_RESPONSE); struct net_device *dev; struct bnep_session *s, *ss; + struct l2cap_conn *conn = NULL; u8 dst[ETH_ALEN], src[ETH_ALEN]; int err; @@ -640,10 +645,18 @@ int bnep_add_connection(struct bnep_conn bnep_set_default_proto_filter(s); #endif - SET_NETDEV_DEV(dev, bnep_get_device(s)); + conn = bnep_get_conn(s); + if (!conn) { + err = -ENOTCONN; + goto failed; + } + + SET_NETDEV_DEV(dev, &conn->hcon->dev); SET_NETDEV_DEVTYPE(dev, &bnep_type); err = register_netdev(dev); + l2cap_conn_put(conn); + conn = NULL; if (err) goto failed; @@ -665,6 +678,8 @@ int bnep_add_connection(struct bnep_conn return 0; failed: + if (conn) + l2cap_conn_put(conn); up_write(&bnep_session_sem); free_netdev(dev); return err;