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From: Johan Hovold <johan@kernel.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Johan Hovold <johan@kernel.org>,
	syzbot <syzbot+0243cb250a51eeefb8cc@syzkaller.appspotmail.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	dmg@turingmachine.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	USB list <linux-usb@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: KASAN: use-after-free Read in adu_disconnect
Date: Fri, 20 Sep 2019 16:31:42 +0200	[thread overview]
Message-ID: <20190920143142.GR30545@localhost> (raw)
In-Reply-To: <CACT4Y+a18nm92r889vJNrwq2518FYMV-cOqiKPQ53VwqwK0oMA@mail.gmail.com>

On Fri, Sep 20, 2019 at 12:08:30PM +0200, Dmitry Vyukov wrote:
> On Fri, Sep 20, 2019 at 12:02 PM Johan Hovold <johan@kernel.org> wrote:
> >
> > On Fri, Sep 20, 2019 at 02:20:00AM -0700, syzbot wrote:
> > > Hello,
> > >
> > > syzbot has tested the proposed patch but the reproducer still triggered
> > > crash:
> > > KASAN: use-after-free Read in adu_interrupt_in_callback

> > This looks like a separate issue, which should be fixed by a separate
> > patch. Not sure how to tell syzbot that. Dmitry?
> 
> There is no way, but also no need. There is nothing it can do with that info.
> If you think it's a separate one and you fixed the first one, mail the
> patch with the first fix.
> Optionally, you can fix the second one as well, and then ask it to
> test a patch with 2 fixes (but you will need either to squash them or
> point to a git tree with both commits).
> 
> > There's is indeed another bug in the driver, which could lead to crashes
> > in the completion handler after clearing the struct usb_device pointer,
> > but possibly also to the above use-after-free if a new device is probed
> > immediately after a disconnect.
> >
> > The below patch addresses both bugs, let's see if that helps.
> >
> > #syz test: https://github.com/google/kasan.git e96407b4

Ok, so I was using an old syzbot kernel from when this was first
reported and apparently hit a second issue which had since been fixed by
Alan.

I was starring at usb-next and couldn't see how it was possible to
trigger this, but that code had Alan's fix 303911cfc5b9 ("USB: core: Fix
races in character device registration and deregistraion").

Guess I had to bitten by this to learn the syzbot interface. ;)

Johan

  parent reply	other threads:[~2019-09-20 14:31 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05 11:58 KASAN: use-after-free Read in adu_disconnect syzbot
2019-08-09 20:24 ` syzbot
2019-09-19 10:35   ` Johan Hovold
2019-09-19 10:53     ` syzbot
2019-09-20  8:26     ` Johan Hovold
2019-09-20  9:02       ` syzbot
2019-09-20  9:08   ` Johan Hovold
2019-09-20  9:13     ` Dmitry Vyukov
2019-09-20  9:21       ` Johan Hovold
2019-09-20  9:28         ` Dmitry Vyukov
2019-09-20  9:35           ` Johan Hovold
2019-09-20 10:05             ` Dmitry Vyukov
2019-09-20  9:20     ` syzbot
2019-09-20 10:02       ` Johan Hovold
2019-09-20 10:08         ` Dmitry Vyukov
2019-09-20 10:16           ` Andrey Konovalov
2019-09-20 14:31           ` Johan Hovold [this message]
2019-09-20 10:21         ` syzbot
2019-09-20 14:38   ` Johan Hovold
2019-09-20 14:58     ` syzbot

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