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

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Date:   Tue, 4 Aug 2020 11:42:53 +0200
From:   Greg KH <greg@...ah.com>
To:     Coiby Xu <coiby.xu@...il.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 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