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Subject: Re: [PATCH -next] drm/meson: Fix potential NULL dereference in
 meson_drv_bind_master()
From:   Neil Armstrong <narmstrong@baylibre.com>
To:     Wei Yongjun <weiyongjun1@huawei.com>,
        David Airlie <airlied@linux.ie>,
        Carlo Caione <carlo@caione.org>,
        Kevin Hilman <khilman@baylibre.com>
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
References: <1521555630-29284-1-git-send-email-weiyongjun1@huawei.com>
 <4cad8099-dbb8-d12c-9ce8-b64688222bd7@baylibre.com>
Organization: Baylibre
Message-ID: <1772626e-c521-a072-76e4-64e3b4883f2e@baylibre.com>
Date:   Tue, 20 Mar 2018 17:16:41 +0100
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On 20/03/2018 16:04, Neil Armstrong wrote:
> On 20/03/2018 15:20, Wei Yongjun wrote:
>> platform_get_resource_byname() 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_byname(pdev, t, n);
>> + if (!res)
>> +   return -EINVAL;
>> ... when != res == NULL
>> e = devm_ioremap(e1, res->start, e2);
>>
>> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
>> ---
>>  drivers/gpu/drm/meson/meson_drv.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
>> index 3baceb7..32b1a6c 100644
>> --- a/drivers/gpu/drm/meson/meson_drv.c
>> +++ b/drivers/gpu/drm/meson/meson_drv.c
>> @@ -197,6 +197,8 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
>>  	priv->io_base = regs;
>>  
>>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hhi");
>> +	if (!res)
>> +		return -EINVAL;
>>  	/* Simply ioremap since it may be a shared register zone */
>>  	regs = devm_ioremap(dev, res->start, resource_size(res));
>>  	if (!regs) {
>> @@ -213,6 +215,8 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
>>  	}
>>  
>>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dmc");
>> +	if (!res)
>> +		return -EINVAL;
>>  	/* Simply ioremap since it may be a shared register zone */
>>  	regs = devm_ioremap(dev, res->start, resource_size(res));
>>  	if (!regs) {
>>
>>
>> _______________________________________________
>> linux-amlogic mailing list
>> linux-amlogic@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-amlogic
>>
> Thanks,
> 
> Acked-by: Neil Armstrong <narmstrong@baylibre.com>
> 

Applied to drm-misc-next