Re: [PATCH v7 09/18] pstore/blk: Introduce backend for block devices

From: Kees Cook <keescook@chromium.org>
To: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Cc: Anton Vorontsov <anton@enomsg.org>,
	Colin Cross <ccross@android.com>, Tony Luck <tony.luck@intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Rob Herring <robh@kernel.org>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mtd@lists.infradead.org
Subject: Re: [PATCH v7 09/18] pstore/blk: Introduce backend for block devices
Date: Mon, 11 May 2020 16:08:59 -0700	[thread overview]
Message-ID: <202005111607.1543AD86A@keescook> (raw)
In-Reply-To: <1f63c624-98aa-52de-a1ef-0a449decf4e9@allwinnertech.com>

On Mon, May 11, 2020 at 04:36:51PM +0800, WeiXiong Liao wrote:
> On 2020/5/11 AM 4:24, Kees Cook wrote:
> > [...]
> > +static struct block_device *psblk_get_bdev(void *holder,
> > +					   struct bdev_info *info)
> 
> Well. That's pretty a good idea to get information about block device
> after registering. And after your codes, the global variable g_bdev_info is
> useless. It's time to drop it.

Ah yes! I meant to clean that up and forgot. Fixed now.

> > [...]
> > +	bdev = blkdev_get_by_path(blkdev, mode, holder);
> > +	if (IS_ERR(bdev)) {
> > +		dev_t devt;
> > +
> > +		devt = name_to_dev_t(blkdev);
> > +		if (devt == 0)
> > +			return ERR_PTR(-ENODEV);
> > +		bdev = blkdev_get_by_dev(devt, mode, holder);
> > +	}
> 
> We should check bdev here. Otherwise, part_nr_sects_read()
> may catch segment error.
> 
> 	if (IS_ERR(bdev))
> 		return bdev;

Whoops, yes. Fixed.

> > +	bdev = psblk_get_bdev(holder, &binfo);
> > +	if (IS_ERR(bdev)) {
> > +		pr_err("failed to open '%s'!\n", blkdev);
> > +		ret = PTR_ERR(bdev);
> > +		goto err_put_bdev;
> 
> It should not goto err_put_bdev since bdev already be put if get_bdev()
> fail.

Ah yes, good point. Fixed.

-- 
Kees Cook