linux-kernel - Re: [PATCH] regulator: fix pointer table overallocation

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Message-ID: <5ef51b56-c533-46c8-621d-7907129594e9@gmail.com>
Date:   Sun, 9 Aug 2020 22:44:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: fix pointer table overallocation

09.08.2020 22:21, Michał Mirosław пишет:
> The code allocates sizeof(regulator_dev) for a pointer. Make it less
> generous. Let kcalloc() calculate the size, while at it.
> 
> Cc: stable@...r.kernel.org
> Fixes: d8ca7d184b33 ("regulator: core: Introduce API for regulators coupling customization")
> Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> ---
>  drivers/regulator/core.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 75ff7c563c5d..9e18997777d3 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -5011,20 +5011,20 @@ static void regulator_remove_coupling(struct regulator_dev *rdev)
>  
>  static int regulator_init_coupling(struct regulator_dev *rdev)
>  {
> +	struct regulator_dev **coupled;
>  	int err, n_phandles;
> -	size_t alloc_size;
>  
>  	if (!IS_ENABLED(CONFIG_OF))
>  		n_phandles = 0;
>  	else
>  		n_phandles = of_get_n_coupled(rdev);
>  
> -	alloc_size = sizeof(*rdev) * (n_phandles + 1);
> -
> -	rdev->coupling_desc.coupled_rdevs = kzalloc(alloc_size, GFP_KERNEL);
> -	if (!rdev->coupling_desc.coupled_rdevs)
> +	coupled = kcalloc(n_phandles + 1, sizeof(*coupled), GFP_KERNEL);
> +	if (!coupled)
>  		return -ENOMEM;
>  
> +	rdev->coupling_desc.coupled_rdevs = coupled;
> +
>  	/*
>  	 * Every regulator should always have coupling descriptor filled with
>  	 * at least pointer to itself.
> 

Hello, Michał! Thank you for the patch! Not sure whether it's worthwhile
to backport this change since it's an improvement, I'll leave it to Mark
to decide, otherwise looks good to me.

Reviewed-by: Dmitry Osipenko <digetx@...il.com>