Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To:     Julia Lawall <julia.lawall@lip6.fr>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        "Sergei Shtylyov (sergei.shtylyov@cogentembedded.com)" 
        <sergei.shtylyov@cogentembedded.com>
Subject: RE: question about drivers/phy/renesas/phy-rcar-gen2.c
Thread-Topic: question about drivers/phy/renesas/phy-rcar-gen2.c
Thread-Index: AQHUu458FqHVOGKcBkGy/69gWAAvIKXx6Sww
Date:   Tue, 26 Feb 2019 08:54:21 +0000
Message-ID: <TY2PR01MB4812FA6549BA23233D9670CBD87B0@TY2PR01MB4812.jpnprd01.prod.outlook.com>
References: <alpine.DEB.2.21.1902030759010.19281@hadrien>
In-Reply-To: <alpine.DEB.2.21.1902030759010.19281@hadrien>
Accept-Language: ja-JP, en-US
Content-Language: ja-JP
received-spf: None (protection.outlook.com: renesas.com does not designate
 permitted sender hosts)
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: ed22f04a-a458-427d-05f8-08d69bc80032
X-MS-Exchange-CrossTenant-originalarrivaltime: 26 Feb 2019 08:54:21.6655
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 53d82571-da19-47e4-9cb4-625a166a4a2a
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-Transport-CrossTenantHeadersStamped: TY2PR01MB2843
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hello,
(Sergei made this code, so I added his email as CC)

I'm sorry for the delayed response.

> From: Julia Lawall, Sent: Sunday, February 3, 2019 4:03 PM
>=20
> Hello,
>=20
> I was wondering whether phy-rcar-gen2.c would use dynamically allocated
> device nodes?

I'm sorry, but what is "dynamically allocated device nodes"?

Best regards,
Yoshihiro Shimoda

>  If so, it looks like the following code could cause a
> use-after-free, due to not incrementing th reference count:
>=20
> 	for_each_child_of_node(dev->of_node, np) {
> 		struct rcar_gen2_channel *channel =3D drv->channels + i;
> 		u32 channel_num;
> 		int error, n;
>=20
> 		channel->of_node =3D np;
> 		...
> 	}
>=20
> On the other hand, if the reference cound it incrememnted, preventing
> memory leaks in the case where the probe function fails would entail some
> complex rewriting of the code, so I thought it would be better to ask
> first.
>=20
> thanks,
> julia