linux-kernel - Re: [PATCH] libnvdimm/of_pmem: Replace kstrdup with devm

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Date:   Fri, 23 Jun 2023 10:17:38 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>, <ira.weiny@...el.com>,
        <dan.j.williams@...el.com>, <vishal.l.verma@...el.com>,
        <dave.jiang@...el.com>, <oohall@...il.com>,
        <aneesh.kumar@...ux.ibm.com>
CC:     <nvdimm@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: Re: [PATCH] libnvdimm/of_pmem: Replace kstrdup with devm_kstrdup and
 add check

Jiasheng Jiang wrote:
> Replace kstrdup() with devm_kstrdup() to avoid memory leak and
> add check for the return value of the devm_kstrdup() to avoid
> NULL pointer dereference
> 
> Fixes: 49bddc73d15c ("libnvdimm/of_pmem: Provide a unique name for bus provider")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>

V2?  references to the first fix and review?

> ---
>  drivers/nvdimm/of_pmem.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/of_pmem.c b/drivers/nvdimm/of_pmem.c
> index 10dbdcdfb9ce..5106dfe0147b 100644
> --- a/drivers/nvdimm/of_pmem.c
> +++ b/drivers/nvdimm/of_pmem.c
> @@ -30,7 +30,12 @@ static int of_pmem_region_probe(struct platform_device *pdev)
>  	if (!priv)
>  		return -ENOMEM;
>  
> -	priv->bus_desc.provider_name = kstrdup(pdev->name, GFP_KERNEL);
> +	priv->bus_desc.provider_name = devm_kstrdup(pdev->name, GFP_KERNEL);

Again, thanks for finding and trying to fix this but you did not even compile
test this.  :-(

/**     
 * devm_kstrdup - Allocate resource managed space and
 *                copy an existing string into that.
 * @dev: Device to allocate memory for
 * @s: the string to duplicate
 * @gfp: the GFP mask used in the devm_kmalloc() call when
 *       allocating memory
 * RETURNS:
 * Pointer to allocated string on success, NULL on failure.
 */     
char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp)
                   ^^^^^^^^^^^^^^^^^^
                   ??????????????????

Ira

> +	if (!priv->bus_desc.provider_name) {
> +		kfree(priv);
> +		return -ENOMEM;
> +	}
> +
>  	priv->bus_desc.module = THIS_MODULE;
>  	priv->bus_desc.of_node = np;
>  
> -- 
> 2.25.1
>