linux-kernel - Re: [PATCH] mfd: fix a potential NULL pointer dereference

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Date:   Mon, 25 Mar 2019 14:43:25 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     Lee Jones <lee.jones@...aro.org>, Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mfd: fix a potential NULL pointer dereference

On 3/25/2019 1:26 PM, Lee Jones wrote:
> On Fri, 22 Mar 2019, Kangjie Lu wrote:
>
>> Hi Lee Jones,
>>
>> Can you review this patch?
> Don't poke.
>
> I have a very long list of reviews on my TODO.  Poking only surfaces
> your patch to the top of my Inbox, and since I review patches in
> reverse chronological order, it puts the review to the back of the
> queue.
>
>>> On Mar 9, 2019, at 2:04 AM, Kangjie Lu <kjlu@....edu> wrote:
>>>
>>> In case devm_kzalloc fails, the fix does NULL check and returns
>>> -ENOMEM upon failure so as to avoid NULL pointer dereference.
>>>
>>> Signed-off-by: Kangjie Lu <kjlu@....edu>
>>> ---
>>> drivers/mfd/sm501.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/mfd/sm501.c b/drivers/mfd/sm501.c
>>> index a530972c5a7e..e0173bf4b0dc 100644
>>> --- a/drivers/mfd/sm501.c
>>> +++ b/drivers/mfd/sm501.c
>>> @@ -1145,6 +1145,9 @@ static int sm501_register_gpio_i2c_instance(struct sm501_devdata *sm,
>>> 	lookup = devm_kzalloc(&pdev->dev,
>>> 			      sizeof(*lookup) + 3 * sizeof(struct gpiod_lookup),
>>> 			      GFP_KERNEL);
>>> +	if (!lookup)
>>> +		return -ENOMEM;

Seems you are using quite old codebase.
This patch is already there ..

https://elixir.bootlin.com/linux/v5.1-rc2/source/drivers/mfd/sm501.c#L1147

commit ae7b8eda27b3( mfd: sm501: Fix potential NULL pointer dereference )


Thanks,
Mukesh


>>> +
>>> 	lookup->dev_id = "i2c-gpio";
>>> 	if (iic->pin_sda < 32)
>>> 		lookup->table[0].chip_label = "SM501-LOW";