netdev - Re: [PATCH net-next] drivers: net: davinci_mdio: fix potential NULL dereference in davinci_mdio

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Date:   Tue, 28 Apr 2020 10:30:01 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     "weiyongjun (A)" <weiyongjun1@...wei.com>,
        David Lechner <david@...hnology.com>,
        Andrew Lunn <andrew@...n.ch>
CC:     "linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH net-next] drivers: net: davinci_mdio: fix potential NULL
 dereference in davinci_mdio_probe()



On 28/04/2020 06:25, weiyongjun (A) wrote:
>>
>> On 4/27/20 4:40 AM, Wei Yongjun wrote:
>>> platform_get_resource() may fail and return NULL, so we should better
>>> check it's return value to avoid a NULL pointer dereference a bit
>>> later in the code.
>>>
>>> This is detected by Coccinelle semantic patch.
>>>
>>> @@
>>> expression pdev, res, n, t, e, e1, e2; @@
>>>
>>> res = \(platform_get_resource\|platform_get_resource_byname\)(pdev, t, n);
>>> + if (!res)
>>> +   return -EINVAL;
>>> ... when != res == NULL
>>> e = devm_ioremap(e1, res->start, e2);
>>>
>>> Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
>>> ---
>>
>> Could we use devm_platform_ioremap_resource() instead?
> 
> We cannot use devm_platform_ioremap_resource() here, see
> Commit 03f66f067560 ("net: ethernet: ti: davinci_mdio: use devm_ioremap()")

Correct, could you add fixed tag as above commit actually introduced an issue:
devm_ioremap_resource() checks input parameters for null.
  
Reviewed-by: Grygorii Strashko <grygorii.strashko@...com>

-- 
Best regards,
grygorii