linux-hardening - Re: [Linux-stm32] [PATCH][next] hwspinlock: stm32: Use struct_size() helper in devm

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Date:   Wed, 26 Jan 2022 09:29:22 +0100
From:   Fabien DESSENNE <fabien.dessenne@...s.st.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Baolin Wang <baolin.wang7@...il.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-hardening@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Linux-stm32] [PATCH][next] hwspinlock: stm32: Use struct_size()
 helper in devm_kzalloc()

Hi Gustavo,

Thank you for the patch.
I am fine with it with a nit picking comment regarding the non-mandatory 
80 characters line break [1].

BR

Fabien

[1] https://lkml.org/lkml/2020/5/29/1038


On 25/01/2022 03:13, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
> 
> Also, address the following sparse warnings:
> drivers/hwspinlock/stm32_hwspinlock.c:84:32: warning: using sizeof on a
> flexible structure
> 
> Link: https://github.com/KSPP/linux/issues/174
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
>   drivers/hwspinlock/stm32_hwspinlock.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwspinlock/stm32_hwspinlock.c
> b/drivers/hwspinlock/stm32_hwspinlock.c
> index 5bd11a7fab65..716ad4401249 100644
> --- a/drivers/hwspinlock/stm32_hwspinlock.c
> +++ b/drivers/hwspinlock/stm32_hwspinlock.c
> @@ -73,15 +73,14 @@ static int stm32_hwspinlock_probe(struct
> platform_device *pdev)
>   	struct device *dev = &pdev->dev;
>   	struct stm32_hwspinlock *hw;
>   	void __iomem *io_base;
> -	size_t array_size;
>   	int i, ret;
>   
>   	io_base = devm_platform_ioremap_resource(pdev, 0);
>   	if (IS_ERR(io_base))
>   		return PTR_ERR(io_base);
>   
> -	array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
> -	hw = devm_kzalloc(dev, sizeof(*hw) + array_size, GFP_KERNEL);
> +	hw = devm_kzalloc(dev, struct_size(hw, bank.lock,
> STM32_MUTEX_NUM_LOCKS),
> +			  GFP_KERNEL);

No need from line break here.


>   	if (!hw)
>   		return -ENOMEM;
>   
>