LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Dmitry Vyukov <dvyukov@google.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	syzbot <syzbot+c7b0ec009a216143df30@syzkaller.appspotmail.com>,
	Hans Verkuil <hverkuil@xs4all.nl>,
	Souptick Joarder <jrdr.linux@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-media@vger.kernel.org, USB list <linux-usb@vger.kernel.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Richard Fontana <rfontana@redhat.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: KASAN: use-after-free Read in usbvision_v4l2_open
Date: Wed, 11 Dec 2019 16:30:06 +0100
Message-ID: <CACT4Y+ZSmwr4y2VrUxZSvFCL0Ws4cp6T5FwyVRg_CqhCf354HQ@mail.gmail.com> (raw)
In-Reply-To: <CAAeHK+xTjUdP5D+DzRD-ZBd-8MmhWxT5n=CqO5u37FrEy6T-8Q@mail.gmail.com>

On Wed, Dec 11, 2019 at 3:23 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Tue, Dec 10, 2019 at 9:13 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > On Tue, 10 Dec 2019, Andrey Konovalov wrote:
> >
> > > On Tue, Dec 10, 2019 at 8:48 PM Alan Stern <stern@rowland.harvard.edu> wrote:
> >
> > > > This looks like a race in v4l2_open(): The function drops the
> > > > videodev_lock mutex before calling the video driver's open routine, and
> > > > the device can be unregistered during the short time between.
> > > >
> > > > This patch tries to make the race much more likely to happen, for
> > > > testing and verification.
> > > >
> > > > Andrey, will syzbot run the same test with this patch, even though it
> > > > says it doesn't have a reproducer?
> > >
> > > Hi Alan,
> > >
> > > No, unfortunately there's nothing to run if there's no reproducer.
> > > It's technically possible to run the same program log that triggered
> > > the bug initially, but since the bug wasn't reproduced with this log
> > > even without the patch, there isn't much sense in running it with the
> > > patch applied.
> >
> > Actually it does make sense.  That bug was caused by a race, and the
> > patch tries to make the race much more likely to happen, so the same
> > test should fail again.
> >
> > But never mind; I'll try a different approach.  There's another syzbot
> > bug report, one with a reproducer, and with this patch in place it
> > should trigger the same race.  I'll try submitting it that way.
> >
> > By the way, do you know why syzbot sent _two_ reply messages?  One with
> > message ID <00000000000031a0af05995eca0b@google.com> and the other with
> > message ID <000000000000441a4205995eca11@google.com>?  It seems like
> > overkill.
>
> Hm, I'm not sure. Dmitry?

I would assume it received 2 emails (second from syzkaller-bugs@
mailing list) and deduplication logic did not work somehow. So it
replied to both.

  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 22:15 syzbot
2019-12-10 19:47 ` Alan Stern
2019-12-10 19:48   ` syzbot
2019-12-10 20:17     ` Alan Stern
2019-12-11 14:23       ` Andrey Konovalov
2019-12-11 15:14         ` Alan Stern
2019-12-11 15:35           ` Dmitry Vyukov
2019-12-12 16:52       ` general protection fault in usb_set_interface Alan Stern
2019-12-10 19:48   ` Re: KASAN: use-after-free Read in usbvision_v4l2_open syzbot
2019-12-10 20:06   ` Andrey Konovalov
2019-12-10 20:13     ` Alan Stern
2019-12-11 14:22       ` Andrey Konovalov
2019-12-11 15:30         ` Dmitry Vyukov [this message]
2019-12-11 16:22           ` Alan Stern
2019-12-12 16:08             ` Andrey Konovalov

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CACT4Y+ZSmwr4y2VrUxZSvFCL0Ws4cp6T5FwyVRg_CqhCf354HQ@mail.gmail.com \
    --to=dvyukov@google.com \
    --cc=andreyknvl@google.com \
    --cc=hverkuil@xs4all.nl \
    --cc=jrdr.linux@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-usb@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=rfontana@redhat.com \
    --cc=stern@rowland.harvard.edu \
    --cc=syzbot+c7b0ec009a216143df30@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git