linux-kernel - Re: [PATCH] Input: synaptics-rmi4: Fix NULL pointer dereference in rmi_driver

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Message-ID: <3e7945e2-1891-4d86-aef9-e19eaa805721@kylinos.cn>
Date: Wed, 17 Jan 2024 15:07:59 +0800
From: Kunwu Chan <chentao@...inos.cn>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: aduggan@...aptics.com, cheiny@...aptics.com, linux-input@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Input: synaptics-rmi4: Fix NULL pointer dereference in
 rmi_driver_probe

On 2024/1/17 03:11, Dmitry Torokhov wrote:
> On Tue, Jan 16, 2024 at 04:38:47PM +0800, Kunwu Chan wrote:
>> devm_kasprintf() returns a pointer to dynamically allocated memory
>> which can be NULL upon failure. Ensure the allocation was successful
>> by checking the pointer validity.
> 
> It is perfectly valid to not set "input->phys" and leave it at NULL. So
> while I agree that having error handling is good I do not believe
> there's chance for NULL pointer dereference, so please adjust your patch
> title.

Thanks for your suggestions.
I'll change patch title to "Input: synaptics-rmi4: Add a null pointer 
check to the rmi_driver_probe".

>>
>> Fixes: 2b6a321da9a2 ("Input: synaptics-rmi4 - add support for Synaptics RMI4 devices")
>> Signed-off-by: Kunwu Chan <chentao@...inos.cn>
>> ---
>>   drivers/input/rmi4/rmi_driver.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
>> index 258d5fe3d395..d3a601ff51e6 100644
>> --- a/drivers/input/rmi4/rmi_driver.c
>> +++ b/drivers/input/rmi4/rmi_driver.c
>> @@ -1197,6 +1197,12 @@ static int rmi_driver_probe(struct device *dev)
>>   		rmi_driver_set_input_params(rmi_dev, data->input);
>>   		data->input->phys = devm_kasprintf(dev, GFP_KERNEL,
>>   						"%s/input0", dev_name(dev));
>> +		if (!data->input->phys) {
>> +			dev_err(dev, "%s: Failed to allocate memory.\n",
> 
> No need to log the error here, memory allocation will already log the
> failure.
Thanks, I'll remove the dev_err.
> 
> Thanks.
> 
-- 
Thanks,
   Kunwu