From: Andrey Konovalov via Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>
To: Phong Tran <tranmanphong@gmail.com>
Cc: alex.theissen@me.com, USB list <linux-usb@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
syzbot+495dab1f175edc9c2f13@syzkaller.appspotmail.com,
2pi@mok.nu, linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [Linux-kernel-mentees] [PATCH] usb: appledisplay: fix use-after-free in bl_get_brightness
Date: Wed, 6 Nov 2019 13:11:09 +0100 [thread overview]
Message-ID: <CAAeHK+zzio=k6aN8rX2meYk1bWiE_TvyzovRkGXm01fbCc_nwA@mail.gmail.com> (raw)
In-Reply-To: <CAAeHK+zKShqnZ=R8KQvVjsfOkAGrWW5jbsXRUnuEY8k4XN3+Fw@mail.gmail.com>
On Wed, Nov 6, 2019 at 1:10 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Wed, Nov 6, 2019 at 12:37 AM Phong Tran <tranmanphong@gmail.com> wrote:
> >
> > In context of USB disconnect, the delaywork trigger and calling
> > appledisplay_bl_get_brightness() and the msgdata was freed.
> >
> > add the checking return value of usb_control_msg() and only update the
> > data while the retval is valid.
> >
> > Reported-by: syzbot+495dab1f175edc9c2f13@syzkaller.appspotmail.com
> > Reported-and-tested-by:
> > syzbot+495dab1f175edc9c2f13@syzkaller.appspotmail.com
> >
> > https://groups.google.com/d/msg/syzkaller-bugs/dRmkh2UYusY/l2a6Mg3FAQAJ
>
> Hi Phong,
>
> FYI, when testing patches with the usb-fuzzer instance, you need to
> provide the same kernel commit id as the one where the bug was
> triggered. Please see here for details:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#usb-bugs
>
> >
> > Signed-off-by: Phong Tran <tranmanphong@gmail.com>
> > ---
> > drivers/usb/misc/appledisplay.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
> > index ac92725458b5..3e3dfa5a3954 100644
> > --- a/drivers/usb/misc/appledisplay.c
> > +++ b/drivers/usb/misc/appledisplay.c
> > @@ -164,7 +164,8 @@ static int appledisplay_bl_get_brightness(struct backlight_device *bd)
> > 0,
> > pdata->msgdata, 2,
> > ACD_USB_TIMEOUT);
> > - brightness = pdata->msgdata[1];
> > + if (retval >= 0)
> > + brightness = pdata->msgdata[1];
> > mutex_unlock(&pdata->sysfslock);
> >
> > if (retval < 0)
> > --
> > 2.20.1
> >
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prev parent reply other threads:[~2019-11-06 12:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <00000000000042d60805933945b5@google.com>
2019-11-05 23:36 ` [Linux-kernel-mentees] [PATCH] usb: appledisplay: fix use-after-free in bl_get_brightness Phong Tran
2019-11-06 11:42 ` Oliver Neukum
2019-11-06 12:26 ` [Linux-kernel-mentees] KASAN: use-after-free Read in appledisplay_bl_get_brightness syzbot
2019-11-06 14:22 ` [Linux-kernel-mentees] [PATCH] usb: appledisplay: fix use-after-free in bl_get_brightness Phong Tran
2019-11-07 8:50 ` Oliver Neukum
2019-11-06 12:10 ` Andrey Konovalov via Linux-kernel-mentees
2019-11-06 12:11 ` Andrey Konovalov via Linux-kernel-mentees [this message]
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