netdev - Re: [Linux-kernel-mentees] [PATCH] Bluetooth: Initialize the TX queue lock when creating struct l2cap

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Message-ID: <20200804104148.nqxcy4f44uga7wjs@Rk>
Date:   Tue, 4 Aug 2020 18:41:48 +0800
From:   Coiby Xu <coiby.xu@...il.com>
To:     Greg KH <greg@...ah.com>
Cc:     linux-bluetooth@...r.kernel.org,
        Johan Hedberg <johan.hedberg@...il.com>,
        "open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        open list <linux-kernel@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        syzbot+fadfba6a911f6bf71842@...kaller.appspotmail.com,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [Linux-kernel-mentees] [PATCH] Bluetooth: Initialize the TX
 queue lock when creating struct l2cap_chan in 6LOWPAN

On Tue, Aug 04, 2020 at 11:42:53AM +0200, Greg KH wrote:
>On Tue, Aug 04, 2020 at 05:39:37PM +0800, Coiby Xu wrote:
>> When L2CAP channel is destroyed by hci_unregister_dev, it will
>> acquire the spin lock of the (struct l2cap_chan *)->tx_q list to
>> delete all the buffers. But sometimes when hci_unregister_dev is
>> being called, this lock may have not bee initialized. Initialize
>> the TX queue lock when creating struct l2cap_chan in 6LOWPAN to fix
>> this problem.
>>
>> Reported-by: syzbot+fadfba6a911f6bf71842@...kaller.appspotmail.com
>> Link: https://syzkaller.appspot.com/bug?extid=fadfba6a911f6bf71842
>> Signed-off-by: Coiby Xu <coiby.xu@...il.com>
>> ---
>>  net/bluetooth/6lowpan.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
>> index bb55d92691b0..713c618a73df 100644
>> --- a/net/bluetooth/6lowpan.c
>> +++ b/net/bluetooth/6lowpan.c
>> @@ -651,6 +651,7 @@ static struct l2cap_chan *chan_create(void)
>>
>>  	l2cap_chan_set_defaults(chan);
>>
>> +	skb_queue_head_init(&chan->tx_q);
>>  	chan->chan_type = L2CAP_CHAN_CONN_ORIENTED;
>>  	chan->mode = L2CAP_MODE_LE_FLOWCTL;
>>  	chan->imtu = 1280;
>
>Nice, did syzbot verify that this resolves the issue?
>
>thanks,
>
>greg k-h

Yes. Thank you for reminding me. I'll also add an Tested-by: tag next time.

--
Best regards,
Coiby