linux-kernel - Re: [PATCH] Drivers: hv: vmbus: Fix memory leak in vmbus_add_channel

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Message-ID: <20220203124432.ckvfzgyyg6fqe2pm@liuwe-devbox-debian-v2>
Date:   Thu, 3 Feb 2022 12:44:32 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Juan Vazquez <juvazq@...ux.microsoft.com>
Cc:     Miaoqian Lin <linmq006@...il.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Drivers: hv: vmbus: Fix memory leak in
 vmbus_add_channel_kobj

On Fri, Jan 28, 2022 at 01:56:04PM -0800, Juan Vazquez wrote:
> On Wed, Jan 26, 2022 at 05:52:46AM +0000, Miaoqian Lin wrote:
> > kobject_init_and_add() takes reference even when it fails.
> > According to the doc of kobject_init_and_add()：
> > 
> >    If this function returns an error, kobject_put() must be called to
> >    properly clean up the memory associated with the object.
> > 
> > Fix memory leak by calling kobject_put().
> > 
> > Fixes: c2e5df616e1a ("vmbus: add per-channel sysfs info")
> > Signed-off-by: Miaoqian Lin <linmq006@...il.com>
> > ---
> >  drivers/hv/vmbus_drv.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index 17bf55fe3169..9e055697783b 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -2028,8 +2028,10 @@ int vmbus_add_channel_kobj(struct hv_device *dev, struct vmbus_channel *channel)
> >  	kobj->kset = dev->channels_kset;
> >  	ret = kobject_init_and_add(kobj, &vmbus_chan_ktype, NULL,
> >  				   "%u", relid);
> > -	if (ret)
> > +	if (ret) {
> > +		kobject_put(kobj);
> >  		return ret;
> > +	}
> >  
> >  	ret = sysfs_create_group(kobj, &vmbus_chan_group);
> If sysfs_create_group() fails same cleanup I think is required.
> 
> Later kobject_uevent() may fail according to doc, but there is no error
> handling, maybe a good moment to consider adding it and do same cleanup.

Miaoqian, are you going to post a new version to address Juan's comment
here?

Thanks,
Wei.

> >  
> > -- 
> > 2.17.1