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Date:   Mon, 12 Sep 2022 14:31:11 +0200
To:     Lee Jones <lee@kernel.org>
Cc:     linux-kernel@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-input@vger.kernel.org
Subject: Re: [RESEND] HID: steam: Prevent NULL pointer dereference in
 steam_{recv,send}_report
From:   "Silvan Jegen" <s.jegen@gmail.com>
References: <20220803111831.387506-1-lee@kernel.org>
 <Yx8cYZnmnN09lD4A@google.com>
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Hi

Lee Jones <lee@kernel.org> wrote:
> On Wed, 03 Aug 2022, Lee Jones wrote:
>=20
> > It is possible for a malicious device to forgo submitting a Feature
> > Report.  The HID Steam driver presently makes no prevision for this
> > and de-references the 'struct hid_report' pointer obtained from the
> > HID devices without first checking its validity.  Let's change that.
>=20
> This patch has been floating around since the beginning of July.
>=20
> It fixes a real issue which was found by creating a virtual
> (software based) malicious device and registering it as a HID device.
>=20
> There is nothing preventing a real attacker from creating a H/W
> version of the device in order to instigate an out-of-bounds read,
> potentially leading to a data leak.
>=20
> Would someone be kind enough to review please?

AFACT this patch has been applied by Jiri on the 25th of August already.

Is a review still needed in this case?


Cheers,

Silvan

>=20
> > Cc: Jiri Kosina <jikos@kernel.org>
> > Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> > Cc: linux-input@vger.kernel.org
> > Fixes: c164d6abf3841 ("HID: add driver for Valve Steam Controller")
> > Signed-off-by: Lee Jones <lee@kernel.org>
> > ---
> >  drivers/hid/hid-steam.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >=20
> > diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
> > index a3b151b29bd71..fc616db4231bb 100644
> > --- a/drivers/hid/hid-steam.c
> > +++ b/drivers/hid/hid-steam.c
> > @@ -134,6 +134,11 @@ static int steam_recv_report(struct steam_device *=
steam,
> >  	int ret;
> > =20
> >  	r =3D steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];=

> > +	if (!r) {
> > +		hid_err(steam->hdev, "No HID_FEATURE_REPORT submitted -  nothing to =
read\n");
> > +		return -EINVAL;
> > +	}
> > +
> >  	if (hid_report_len(r) < 64)
> >  		return -EINVAL;
> > =20
> > @@ -165,6 +170,11 @@ static int steam_send_report(struct steam_device *=
steam,
> >  	int ret;
> > =20
> >  	r =3D steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];=

> > +	if (!r) {
> > +		hid_err(steam->hdev, "No HID_FEATURE_REPORT submitted -  nothing to =
read\n");
> > +		return -EINVAL;
> > +	}
> > +
> >  	if (hid_report_len(r) < 64)
> >  		return -EINVAL;
> > =20