linux-kernel - Re: [syzbot] Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each

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Message-ID: <67252c5d.050a0220.35b515.0176.GAE@google.com>
Date: Fri, 01 Nov 2024 12:30:37 -0700
From: syzbot <syzbot+6cf5652d3df49fae2e3f@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()

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***

Subject: Re: [PATCH v2] Bluetooth: fix use-after-free in device_for_each_child()
Author: luiz.dentz@...il.com

On Fri, Nov 1, 2024 at 1:37 PM Luiz Augusto von Dentz
<luiz.dentz@...il.com> wrote:
>
> Hi Dmitry,
>
> On Fri, Nov 1, 2024 at 11:31 AM Luiz Augusto von Dentz
> <luiz.dentz@...il.com> wrote:
> >
> > Hi Dmitry,
> >
> > On Fri, Nov 1, 2024 at 11:17 AM Dmitry Antipov <dmantipov@...dex.ru> wrote:
> > >
> > > On 11/1/24 6:12 PM, Luiz Augusto von Dentz wrote:
> > >
> > > > There is no Tested-by thus why I assumed it wasn't tested by syzbot yet.
> > >
> > > Ugh. Until today I've assumed that Tested-by: is applicable to human-driven
> > > testing only :-).
> >
> > Nope, in fact it is very handy to have syzbot test your changes since
> > it may hit other problems as well.
>
> Looks like this doesn't solve the problem, in fact I think you are
> getting it backwards, you are trying to reparent the parent dev not
> the child and I assume by destroying the parent device there should be
> some way to reset the parent which seems to be the intent the
> following code in hci_conn_del_sysfs:
>
>     while (1) {
>         struct device *dev;
>
>         dev = device_find_child(&conn->dev, NULL, __match_tty);
>         if (!dev)
>             break;
>         device_move(dev, NULL, DPM_ORDER_DEV_LAST);
>         put_device(dev);
>     }
>
> But note that it only does that after matching tty, but I guess we
> want to do it regardless otherwise we may have the child objects still
> access it, that said we should probably use device_for_each_child
> though if that is safe to do calls to device_move under its callback.

#syz test

> > > Dmitry
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz
>
>
>
> --
> Luiz Augusto von Dentz



-- 
Luiz Augusto von Dentz