Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
Message-ID: <2508da6b-a099-4271-a1d0-04cfe5d39daf@weidmueller.com>
Date:   Mon, 20 Nov 2023 13:38:06 +0100
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] net: phy: Fix potential null pointer access
To:     "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc:     Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Lukas Funke <lukas.funke@weidmueller.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20231120093256.3642327-1-lukas.funke-oss@weidmueller.com>
 <ZVssJrplePACN3of@shell.armlinux.org.uk>
From:   Lukas Funke <lukas.funke-oss@weidmueller.com>
In-Reply-To: <ZVssJrplePACN3of@shell.armlinux.org.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?YlR4eWpPWERvQ3dMUEJzZWRhUnUxYlpYWkF3NG11NWtWY0s5R3pDMEdwSURx?=
 =?utf-8?B?WkNUc202NzNVRmpBeERYL1hDRzZKWTZpR2ZQNVlrak5WaVVPS2NIay9ZUEFs?=
 =?utf-8?B?RjRhRFdpZ0gyMWN6Y213QlZRa3RvMVp5U2VUV0JFblhVMitkTTB2N2piNDgz?=
 =?utf-8?B?R2ZIMWdaSm5EZEYzSWN6SGlKVmlmeWF3KzRodmo1bkVUSy9xeTJFVkRoVWRz?=
 =?utf-8?B?ZDllRnhrMWxSNit6TUJZTmNNcWxpdmFnRys4R3JOZUpIUCtjVWd3b01xeTBh?=
 =?utf-8?B?aVdadWp6KytDWVRsb1cydGVDZzQ3WlFCS2t6YmIwZlZYN2k4eGdDR0J2SWlR?=
 =?utf-8?B?eUpyWUNWdW9kaFBCdkRyMy9ubXVLRy9BRGthdEVpbGhUR1FmazhjOXVpVTBx?=
 =?utf-8?B?ancvVnlwTUFiRkZMWlVGZC9ROFdBcVJVYVRHRC9EVnV4ZWpOYVNFSTY2NnVj?=
 =?utf-8?B?TGhhcHcrNmgwRU9rOXk4NXpnYjR3M2Qwa3JvMGw1QTNhQkRsUzBvQnAxeU5R?=
 =?utf-8?B?UmhGTWtSZ0VTOXhOcTh4bnQ5YXFhV2creFFnQkZUUjV5TVN3K0x3VGlISFpX?=
 =?utf-8?B?QmVDeGpOdHQwWS9ESHlJL3EzRzVIdi9DKzBZanRSQlBmM0sveklYTHBtcVZ0?=
 =?utf-8?B?UGxaMXhiUVFsL0xQWUE3ZFU5akxqdGVzWXNFdVhkTEhkQlZmM2ZLT3Q4WkJP?=
 =?utf-8?B?YmZ0MnBQcWo3N0lGZW03T280RXh4b2xmY2N0WUFqUXdNczFFYzBvZXIrSExE?=
 =?utf-8?B?ekRPTXZ4ei9oZzhXbjU1TWlHb3o2QUpoMXExOW9sd01kdFhUaVJlZzhnc0RI?=
 =?utf-8?B?TWFTOXJYMWZMSmpRelhUU0huckFOUVNvV1Y5V0QySjlQUlhVZXFnL29ORXhP?=
 =?utf-8?B?L2tiOW10K3psVFNLUmQ2TnpPc1hXS2lHamZLVFRCM3JnY0t1TUc5OWdhT2VE?=
 =?utf-8?B?b0ZHUExZZXFJSWVoS1d4Wk1zWXV0WVN1QnRUbFRudE5ka0tzam5LdHhINHJJ?=
 =?utf-8?B?ekpRTzR2bk0zNGRRS2czTzg1dkxpc2dPT2Y2czI5R1dGVWZ6eWVUb1V6TkRW?=
 =?utf-8?B?VEpuWi9rWXdjRFREeXdhcFVndXBpQzNhREpxbHg1alJPZmNtYWsxR2lNYnF1?=
 =?utf-8?B?TU5zYWdzTU02ck1qUkl0QmNlRUUxa2srRlVlSmpBVHIzditnQjZKK3BTWjV4?=
 =?utf-8?B?YmZUU3NDN1E4U245c1JjYjliQnVJMUlja1lDZEhtbTdXOVJjQS9tRExBZTky?=
 =?utf-8?B?SHpOZFBKdCtLVndCZG1udU1QSUt4NkFPcGdRY1JiV0FJNFJsYXB1ZllySXUy?=
 =?utf-8?B?d1ZuenI4K2lyT3p2bzNxRCttU3d4eHV5QnhsU096T0NBOWd0QmJ5TTZtd0NF?=
 =?utf-8?B?VmZkd3JyNDUvRFhHTHp1Z3podm5adVViMkw0TDJES0piSy9BbmpTM2RTbmpt?=
 =?utf-8?B?K1hqbjUwdm1BZzhJWlRxVjg4SVFNUndad0ZjUVVSL1VtdlFYcjNBTTQwQSt0?=
 =?utf-8?B?ZlhtMnVjUnRHN0xBemZ0a0twSHlxVEg3bklyNGRxNXZWVGtXWDlQaFNhd2ZJ?=
 =?utf-8?B?d3VZYk40MzJaYmt0cUhycElud2FEb0FkaGRDSWlFLzlQQnFjUkNvN2xLdnVJ?=
 =?utf-8?B?VWdlZFFESGI0RHJISzdIaW5mQ1NJRzNiM3JlaE5TakJpMXdsN3VFb0hvMlZC?=
 =?utf-8?B?TTBrSHZpUmtybE0rZWJYSnRPNHFmYkNXRnB4OVlnSkRzMW5MSTZkUFgrbHY1?=
 =?utf-8?B?ZHBMS3RWOHhSc2tMZktqZ1pKOEYxNHJXOVRnbFhIMGRrdlBhTXRreXBVdXEz?=
 =?utf-8?B?eEV5NGh6SiswV2hZS3AzMjhCdENzbElQZzhlV1JsTnp5OEd4VlFzUEhXMlIv?=
 =?utf-8?B?UTBLcWpmV2UxT3RsK0QzWS9QMlQzVUtrRmR2MThxMHZhVnFMdS9iRkZ3UERF?=
 =?utf-8?B?eHQ5ZjU5RnRocFg0cTZGdXJqQ1R3NERjblpsd1Y4VnRSaFloa2wyUk5UTnVW?=
 =?utf-8?B?Tm1zZmhUcGhBek9EYjd2TTRlVmMydW5SdW4vODR5UVlLcmREcjVqUjEwZVdW?=
 =?utf-8?B?a01laGNDTVNqejBCSmdsMzloY1NTejQwR3Q1Qk5mVkFPZlhtWXpkTlR2UWUz?=
 =?utf-8?B?aUxpVWFvb3J2N1Yza042NE40RkJIaUg5QmJHdnlRV3FWM0hzY1RmN1JPZ0xO?=
 =?utf-8?B?Vnc9PQ==?=
X-OriginatorOrg: weidmueller.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 2b9c3ee6-50c8-4591-7a91-08dbe9c58c82
X-MS-Exchange-CrossTenant-AuthSource: AS2PR08MB8431.eurprd08.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Nov 2023 12:38:07.9141
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: e4289438-1c5f-4c95-a51a-ee553b8b18ec
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 44JFihAr8TGUvV4Iz0qAHv6IB6y/EeTvgNCjq7dKcsutnxPK441bOUurhZtAN597/c2imokc4PXtlZ+7JzUCPQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: GVXPR08MB7773
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,
        SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no
        version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Mon, 20 Nov 2023 04:38:19 -0800 (PST)

Hi Russel,

On 20.11.2023 10:51, Russell King (Oracle) wrote:
> On Mon, Nov 20, 2023 at 10:32:54AM +0100, Lukas Funke wrote:
>> From: Lukas Funke <lukas.funke@weidmueller.com>
>>
>> When there is no driver associated with the phydev, there will be a
>> nullptr access. The commit checks if the phydev driver is set before
>> access.
> 
> What's the call path that we encounter a NULL drv pointer?


The patch is a bit older and the path is reconstructed from my memory:

macb_phylink_connect -> phylink_of_phy_connect -> of_phy_connect -> 
phy_connect_direct -> phy_request_interrupt

It happend when we used the Xilinx gmii2rgmii phy driver. We did a 
missconfiguration in the dt and bumped into the nullpointer exception. 
Since other functions like phy_aneg_done() also check for driver 
existence I thought it would be a good addition.

> 
> Thanks.
>