linux-kernel - Re: [PATCH -next,v2] nvmem: core: Fix memleak in nvmem

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Date:   Mon, 18 Jul 2022 12:44:45 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Gaosheng Cui <cuigaosheng1@...wei.com>, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, gongruiqi1@...wei.com,
        wangweiyang2@...wei.com
Subject: Re: [PATCH -next,v2] nvmem: core: Fix memleak in nvmem_register()



On 16/07/2022 10:52, Gaosheng Cui wrote:
> dev_set_name will alloc memory for nvmem->dev.kobj.name in
> nvmem_register, when nvmem_validate_keepouts failed, nvmem's
> memory will be freed and return, but nobody will free memory
> for nvmem->dev.kobj.name, there will be memleak, so moving
> dev_set_name after nvmem_validate_keepouts to fix it.
> 
> Fixes: de0534df9347 ("nvmem: core: fix error handling while validating keepout regions")
> Signed-off-by: Gaosheng Cui <cuigaosheng1@...wei.com>
> ---
>   drivers/nvmem/core.c | 28 ++++++++++++++--------------
>   1 file changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 1e3c754efd0d..a5d75edf509d 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -808,20 +808,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
>   	else if (!config->no_of_node)
>   		nvmem->dev.of_node = config->dev->of_node;
>   
> -	switch (config->id) {
> -	case NVMEM_DEVID_NONE:
> -		dev_set_name(&nvmem->dev, "%s", config->name);
> -		break;
> -	case NVMEM_DEVID_AUTO:
> -		dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
> -		break;
> -	default:
> -		dev_set_name(&nvmem->dev, "%s%d",
> -			     config->name ? : "nvmem",
> -			     config->name ? config->id : nvmem->id);
> -		break;
> -	}
> -
>   	nvmem->read_only = device_property_present(config->dev, "read-only") ||
>   			   config->read_only || !nvmem->reg_write;
>   
> @@ -838,6 +824,20 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
>   		}
>   	}
>   
> +	switch (config->id) {
> +	case NVMEM_DEVID_NONE:
> +		dev_set_name(&nvmem->dev, "%s", config->name);
> +		break;
> +	case NVMEM_DEVID_AUTO:
> +		dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
> +		break;
> +	default:
> +		dev_set_name(&nvmem->dev, "%s%d",
> +			     config->name ? : "nvmem",
> +			     config->name ? config->id : nvmem->id);
> +		break;
> +	}
> +
The issue with this approach is that dev_err messages in 
nvmem_validate_keepouts() will show up without device name setup.

I think better option is to move nvmem_validate_keepouts() after 
device_register() and let the device core deal with cleaning name in 
error cases.

--srini

>   	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
>   
>   	rval = device_register(&nvmem->dev);