linux-kernel - Re: [PATCH] nvmem: core: add sanity check in nvmem_device

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Date:   Tue, 4 Aug 2020 12:58:15 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Bingbu Cao <bingbu.cao@...el.com>
Cc:     srinivas.kandagatla@...aro.org, linux-kernel@...r.kernel.org,
        bingbu.cao@...ux.intel.com
Subject: Re: [PATCH] nvmem: core: add sanity check in nvmem_device_read()

Hi Bingbu,

Thank you for the patch.

On Tue, Aug 04, 2020 at 05:13:56PM +0800, Bingbu Cao wrote:
> nvmem_device_read() could be called directly once nvmem device
> registered, the sanity check should be done before call
> nvmem_reg_read() as cell and sysfs read did now.
> 
> Signed-off-by: Bingbu Cao <bingbu.cao@...el.com>
> ---
>  drivers/nvmem/core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 927eb5f6003f..c9a77993f008 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -1491,6 +1491,13 @@ int nvmem_device_read(struct nvmem_device *nvmem,
>  	if (!nvmem)
>  		return -EINVAL;
>  
> +	if (offset >= nvmem->size || bytes < nvmem->word_size)
> +		return 0;
> +
> +	if (bytes + offset > nvmem->size)
> +		bytes = nvmem->size - offset;

The check is relevant for nvmem_device_write(), too.

There are also other ways to access nvmem devices such as nvmem_cell_read
and others alike. Should they be considered as well?

> +
> +	bytes = round_down(bytes, nvmem->word_size);
>  	rc = nvmem_reg_read(nvmem, offset, buf, bytes);
>  
>  	if (rc)

-- 
Kind regards,

Sakari Ailus