linux-kernel - Re: [PATCH] libnvdimm/of_pmem: Add check and kfree for kstrdup

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Date:   Thu, 22 Jun 2023 22:38:00 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     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: Add check and kfree for kstrdup

On Wed, Jun 21, 2023 at 00:04:36 +0800, Ira Weiny wrote:
> Ira Weiny wrote:
>> Jiasheng Jiang wrote:
>> > Add check for the return value of kstrdup() and return the error
>> > if it fails in order to avoid NULL pointer dereference.
>> > Moreover, use kfree() in the later error handling in order to avoid
>> > memory leak.
>> > 
>> > Fixes: 49bddc73d15c ("libnvdimm/of_pmem: Provide a unique name for bus provider")
>> > Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
>> > ---
>> >  drivers/nvdimm/of_pmem.c | 6 ++++++
>> >  1 file changed, 6 insertions(+)
>> > 
>> > diff --git a/drivers/nvdimm/of_pmem.c b/drivers/nvdimm/of_pmem.c
>> > index 10dbdcdfb9ce..fe6edb7e6631 100644
>> > --- a/drivers/nvdimm/of_pmem.c
>> > +++ b/drivers/nvdimm/of_pmem.c
>> > @@ -31,11 +31,17 @@ static int of_pmem_region_probe(struct platform_device *pdev)
>> >  		return -ENOMEM;
>> >  
>> >  	priv->bus_desc.provider_name = kstrdup(pdev->name, GFP_KERNEL);
>> > +	if (!priv->bus_desc.provider_name) {
>> > +		kfree(priv);
>> > +		return -ENOMEM;
>> > +	}
>> > +
>> >  	priv->bus_desc.module = THIS_MODULE;
>> >  	priv->bus_desc.of_node = np;
>> >  
>> >  	priv->bus = bus = nvdimm_bus_register(&pdev->dev, &priv->bus_desc);
>> >  	if (!bus) {
>> > +		kfree(priv->bus_desc.provider_name);
>> 
>> Nice catch!
>> 
>> However, this free needs to happen in of_pmem_region_remove() as well.
> 
> Looks like the mail from my phone had html in it.  Sorry for that.
> 
> This would be better with devm_kstrdup() and then we don't have to worry
> about the kfree at all.

Looks good.
I have submitted a new patch "libnvdimm/of_pmem: Replace kstrdup with devm_kstrdup and add check".
Since the titie has been modified, I did not submitted a v2.

- Jiasheng Jiang