linux-kernel - Re: [PATCH] clk: microchip: check for null return of devm

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Message-ID: <666f8502-86dd-b000-92d2-ec3fd90e332d@microchip.com>
Date:   Fri, 25 Nov 2022 13:48:48 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <conor@...nel.org>, <tanghui20@...wei.com>
CC:     <mturquette@...libre.com>, <sboyd@...nel.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yusongping@...wei.com>, <Conor.Dooley@...rochip.com>
Subject: Re: [PATCH] clk: microchip: check for null return of devm_kzalloc()

On 19.11.2022 12:43, Conor Dooley wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Sat, Nov 19, 2022 at 01:48:58PM +0800, Hui Tang wrote:
>> Because of the possilble failure of devm_kzalloc(), name might be NULL and
>> will cause null pointer derefrence later.
> 
> In theory, yeah?
> 
> (note to self, s/refrence/reference/, s/possilble/possible)

Applied to clk-microchip-fixes with these adjustments, thanks!

> 
>> Therefore, it might be better to check it and directly return -ENOMEM.
> 
> I agree with your use of might here. If the allocations do fail, we
> likely aren't getting the system off the ground anyway - but there is
> no harm in checking.
> 
> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> 
> @Claudiu, supposedly I can push to the at91 repo now so I will try to do
> that.
> 
> Thanks,
> Conor.
> 
>>
>> Fixes: d39fb172760e ("clk: microchip: add PolarFire SoC fabric clock support")
>> Signed-off-by: Hui Tang <tanghui20@...wei.com>
>> ---
>>  drivers/clk/microchip/clk-mpfs-ccc.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/clk/microchip/clk-mpfs-ccc.c b/drivers/clk/microchip/clk-mpfs-ccc.c
>> index 7be028dced63..32aae880a14f 100644
>> --- a/drivers/clk/microchip/clk-mpfs-ccc.c
>> +++ b/drivers/clk/microchip/clk-mpfs-ccc.c
>> @@ -166,6 +166,9 @@ static int mpfs_ccc_register_outputs(struct device *dev, struct mpfs_ccc_out_hw_
>>               struct mpfs_ccc_out_hw_clock *out_hw = &out_hws[i];
>>               char *name = devm_kzalloc(dev, 23, GFP_KERNEL);
>>
>> +             if (!name)
>> +                     return -ENOMEM;
>> +
>>               snprintf(name, 23, "%s_out%u", parent->name, i);
>>               out_hw->divider.hw.init = CLK_HW_INIT_HW(name, &parent->hw, &clk_divider_ops, 0);
>>               out_hw->divider.reg = data->pll_base[i / MPFS_CCC_OUTPUTS_PER_PLL] +
>> @@ -200,6 +203,9 @@ static int mpfs_ccc_register_plls(struct device *dev, struct mpfs_ccc_pll_hw_clo
>>               struct mpfs_ccc_pll_hw_clock *pll_hw = &pll_hws[i];
>>               char *name = devm_kzalloc(dev, 18, GFP_KERNEL);
>>
>> +             if (!name)
>> +                     return -ENOMEM;
>> +
>>               pll_hw->base = data->pll_base[i];
>>               snprintf(name, 18, "ccc%s_pll%u", strchrnul(dev->of_node->full_name, '@'), i);
>>               pll_hw->name = (const char *)name;
>> --
>> 2.17.1
>>