linux-kernel - Re: [Openipmi-developer] [PATCH] ipmi: Use devm

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Message-ID: <ZtjV5DoZXPYM1NJx@mail.minyard.net>
Date: Wed, 4 Sep 2024 16:49:24 -0500
From: Corey Minyard <corey@...yard.net>
To: Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: zhangjiao2 <zhangjiao2@...s.chinamobile.com>,
	openipmi-developer@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, minyard@....org
Subject: Re: [Openipmi-developer] [PATCH] ipmi: Use devm_kasprintf

On Wed, Sep 04, 2024 at 07:41:32PM +0200, Christophe JAILLET via Openipmi-developer wrote:
> Le 04/09/2024 à 06:12, zhangjiao2 a écrit :
> > From: zhang jiao <zhangjiao2@...s.chinamobile.com>
> > 
> > Use devm_kasprintf to simplify code.
> 
> Hi,
> 
> I don't think that it is correct because __ipmi_bmc_register() is not a
> probe function ans is not called from a probe function. So it is really
> unlikely that a devm_ function is correct.
> 
> The kasprintf() you are removing is balanced by a kfree() in
> __ipmi_bmc_unregister().
> So you patch would lead to a potential double-free issue.

Yes, this is incorrect from a number of points of view.

-corey

> 
> CJ
> 
> > 
> > Signed-off-by: zhang jiao <zhangjiao2@...s.chinamobile.com>
> > ---
> >   drivers/char/ipmi/ipmi_msghandler.c | 9 ++-------
> >   1 file changed, 2 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> > index e12b531f5c2f..5d78b1fe49a8 100644
> > --- a/drivers/char/ipmi/ipmi_msghandler.c
> > +++ b/drivers/char/ipmi/ipmi_msghandler.c
> > @@ -3213,7 +3213,7 @@ static int __ipmi_bmc_register(struct ipmi_smi *intf,
> >   	if (intf_num == -1)
> >   		intf_num = intf->intf_num;
> > -	intf->my_dev_name = kasprintf(GFP_KERNEL, "ipmi%d", intf_num);
> > +	intf->my_dev_name = devm_kasprintf(intf->si_dev, GFP_KERNEL, "ipmi%d", intf_num);
> >   	if (!intf->my_dev_name) {
> >   		rv = -ENOMEM;
> >   		dev_err(intf->si_dev, "Unable to allocate link from BMC: %d\n",
> > @@ -3226,7 +3226,7 @@ static int __ipmi_bmc_register(struct ipmi_smi *intf,
> >   	if (rv) {
> >   		dev_err(intf->si_dev, "Unable to create symlink to bmc: %d\n",
> >   			rv);
> > -		goto out_free_my_dev_name;
> > +		goto out_unlink1;
> >   	}
> >   	intf->bmc_registered = true;
> > @@ -3237,11 +3237,6 @@ static int __ipmi_bmc_register(struct ipmi_smi *intf,
> >   	intf->in_bmc_register = false;
> >   	return rv;
> > -
> > -out_free_my_dev_name:
> > -	kfree(intf->my_dev_name);
> > -	intf->my_dev_name = NULL;
> > -
> >   out_unlink1:
> >   	sysfs_remove_link(&intf->si_dev->kobj, "bmc");
> 
> 
> 
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