linux-kernel - Re: [RFC PATCH] use dev_set_name(,NULL) to prevent leaking

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Date:	Tue, 28 Apr 2009 08:39:06 -0700
From:	Greg KH <gregkh@...e.de>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Kay Sievers <kay.sievers@...y.org>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [RFC PATCH] use dev_set_name(,NULL) to prevent leaking

On Tue, Apr 28, 2009 at 08:34:29AM -0700, Yinghai Lu wrote:
> Yinghai Lu wrote:
> > Kay Sievers wrote:
> >> On Tue, Apr 28, 2009 at 09:42, Yinghai Lu <yinghai@...nel.org> wrote:
> >>> those about 1/3 dev_set_name() etc.
> >> put_device()?
> >>
> >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/base/core.c;h=4aa527b8a91381289eb175b33f46e3e418d10374;hb=HEAD#l848
> >>
> > ok, normal release path seems right, put_device will free the name.
> > 
> > how about other fail path, that there is not put_device involved?
> > 
>  
> looks like need to follow this pattern
> 
> static int
> sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
>                       struct sa1111_dev_info *info)
> {
>         struct sa1111_dev *dev;
>         int ret;
> 
>         dev = kzalloc(sizeof(struct sa1111_dev), GFP_KERNEL);
>         if (!dev) {
>                 ret = -ENOMEM;
>                 goto out;
>         }
> 
>         dev_set_name(&dev->dev, "%4.4lx", info->offset);
>         dev->devid       = info->devid;
>         dev->dev.parent  = sachip->dev;
>         dev->dev.bus     = &sa1111_bus_type;
>         dev->dev.release = sa1111_dev_release;
>         dev->dev.coherent_dma_mask = sachip->dev->coherent_dma_mask;
>         dev->res.start   = sachip->phys + info->offset;
>         dev->res.end     = dev->res.start + 511;
>         dev->res.name    = dev_name(&dev->dev);
>         dev->res.flags   = IORESOURCE_MEM;
>         dev->mapbase     = sachip->base + info->offset;
>         dev->skpcr_mask  = info->skpcr_mask;
>         memmove(dev->irq, info->irq, sizeof(dev->irq));
> 
>         ret = request_resource(parent, &dev->res);
>         if (ret) {
>                 printk("SA1111: failed to allocate resource for %s\n",
>                         dev->res.name);
>                 dev_set_name(&dev->dev, NULL); ============> clear the name
>                 kfree(dev);
>                 goto out;
>         }
>         
> 
>         ret = device_register(&dev->dev);
>         if (ret) {
>                 release_resource(&dev->res);
>                 put_device(&dev->dev);   ==================> put the device...
>                 kfree(dev);
>                 goto out;
>         }

You can just do a "put_device()" in both places, and it should be fine.

thanks,

greg k-h
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