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

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Message-ID: <202005111607.1543AD86A@keescook>
Date:   Mon, 11 May 2020 16:08:59 -0700
From:   Kees Cook <keescook@...omium.org>
To:     WeiXiong Liao <liaoweixiong@...winnertech.com>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Rob Herring <robh@...nel.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v7 09/18] pstore/blk: Introduce backend for block devices

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