Subject: Re: [v2] net:ethernet:cavium:octeon:octeon_mgmt: Handle return NULL
 error from devm_ioremap
To: Arvind Yadav <arvind.yadav.cs@gmail.com>, <peter.chen@nxp.com>,
        <fw@strlen.de>, <david.daney@cavium.com>
References: <1481732732-6892-1-git-send-email-arvind.yadav.cs@gmail.com>
CC: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From: David Daney <ddaney@caviumnetworks.com>
Message-ID: <3c3d5968-bc41-e1b7-6fda-78e92e7a9d56@caviumnetworks.com>
Date: Wed, 14 Dec 2016 09:32:46 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.5.1
MIME-Version: 1.0
In-Reply-To: <1481732732-6892-1-git-send-email-arvind.yadav.cs@gmail.com>
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Dec 2016 17:32:49.8893 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1PR07MB2143
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1213
Lines: 37

On 12/14/2016 08:25 AM, Arvind Yadav wrote:
> Here, If devm_ioremap will fail. It will return NULL.
> Kernel can run into a NULL-pointer dereference.
> This error check will avoid NULL pointer dereference.
>

Have you ever seen this failure in the wild?

How was the patch tested?

Thanks,
David Daney


> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
>  drivers/net/ethernet/cavium/octeon/octeon_mgmt.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
> index 4ab404f..33c2fec 100644
> --- a/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
> +++ b/drivers/net/ethernet/cavium/octeon/octeon_mgmt.c
> @@ -1479,6 +1479,12 @@ static int octeon_mgmt_probe(struct platform_device *pdev)
>  	p->agl = (u64)devm_ioremap(&pdev->dev, p->agl_phys, p->agl_size);
>  	p->agl_prt_ctl = (u64)devm_ioremap(&pdev->dev, p->agl_prt_ctl_phys,
>  					   p->agl_prt_ctl_size);
> +	if (!p->mix || !p->agl || !p->agl_prt_ctl) {
> +		dev_err(&pdev->dev, "failed to map I/O memory\n");
> +		result = -ENOMEM;
> +		goto err;
> +	}
> +
>  	spin_lock_init(&p->lock);
>
>  	skb_queue_head_init(&p->tx_list);
>