Received-SPF: pass (google.com: best guess record for domain of linux-bluetooth-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <1583589488-22450-1-git-send-email-hqjagain@gmail.com> <449B4F83-8BCD-413C-823B-C7A5554801FB@holtmann.org>
In-Reply-To: <449B4F83-8BCD-413C-823B-C7A5554801FB@holtmann.org>
From:   Qiujun Huang <hqjagain@gmail.com>
Date:   Sun, 8 Mar 2020 16:27:02 +0800
Message-ID: <CAJRQjodmk0BDa=i4JeB0MSW6NJ5tVyx5TRLReORxFbQueY4WQw@mail.gmail.com>
Subject: Re: [PATCH] bluetooth/rfcomm: fix ODEBUG bug in rfcomm_dev_ioctl
To:     Marcel Holtmann <marcel@holtmann.org>
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Bluez mailing list <linux-bluetooth@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

On Sun, Mar 8, 2020 at 4:18 PM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Qiujun,
>
> > Needn't call 'rfcomm_dlc_put' here, because 'rfcomm_dlc_exists' didn't
> > increase dlc->refcnt.
> >
> > Reported-by: syzbot+4496e82090657320efc6@syzkaller.appspotmail.com
> > Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
> > ---
> > net/bluetooth/rfcomm/tty.c | 1 -
> > 1 file changed, 1 deletion(-)
> >
> > diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
> > index 0c7d31c..ea2a1df0 100644
> > --- a/net/bluetooth/rfcomm/tty.c
> > +++ b/net/bluetooth/rfcomm/tty.c
> > @@ -414,7 +414,6 @@ static int __rfcomm_create_dev(struct sock *sk, void __user *arg)
> >               if (IS_ERR(dlc))
> >                       return PTR_ERR(dlc);
> >               else if (dlc) {
> > -                     rfcomm_dlc_put(dlc);
> >                       return -EBUSY;
> >               }
> >               dlc = rfcomm_dlc_alloc(GFP_KERNEL);
>
> Please see the proposed change from Hillf.
>
> It is better to not bother with the else if here since the if statement will already leave the function.

I get that. Thanks.

>
>         if (dlc)
>                 return -EBUSY;
>
> Regards
>
> Marcel
>