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

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Message-ID: <6491ce14cc4b4_483a29487@iweiny-mobl.notmuch>
Date:   Tue, 20 Jun 2023 09:04:36 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Ira Weiny <ira.weiny@...el.com>,
        Jiasheng Jiang <jiasheng@...as.ac.cn>,
        <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

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.

Ira