Re: [Linux-kernel-mentees] [PATCH] Bluetooth: Initialize the TX queue lock when creating struct l2cap_chan in 6LOWPAN

[Coiby Xu]

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@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Link: https://syzkaller.appspot.com/bug?extid=fadfba6a911f6bf71842
> > Signed-off-by: Coiby Xu <coiby.xu@xxxxxxxxx>
> > ---
> >  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