linux-kernel - Re: [PATCH v7 1/3] Staging: zram: Fix access of NULL pointer

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Date:	Wed, 30 Oct 2013 11:36:27 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Rashika Kheria <rashika.kheria@...il.com>
Cc:	opw-kernel@...glegroups.com,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Nitin Gupta <ngupta@...are.org>,
	Jerome Marchand <jmarchand@...hat.com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v7 1/3] Staging: zram: Fix access of NULL pointer

On Wed, Oct 30, 2013 at 04:40:54AM +0530, Rashika Kheria wrote:
> This patch fixes the bug in reset_store caused by accessing NULL pointer.
> 
> The bdev gets its value from bdget_disk() which could fail when memory
> pressure is severe and hence can return NULL because allocation of
> inode in bdget could fail.
> 
> Hence, this patch introduces a check for bdev to prevent reference to a
> NULL pointer in the later part of the code. It also removes unnecessary
> check of bdev for fsync_bdev().
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Rashika Kheria <rashika.kheria@...il.com>
> ---
> 
> This patch fixes the following issues of the previous revision-
> Better Description
> 
>  drivers/staging/zram/zram_drv.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> index 2c4ed52..d640a8f 100644
> --- a/drivers/staging/zram/zram_drv.c
> +++ b/drivers/staging/zram/zram_drv.c
> @@ -648,6 +648,9 @@ static ssize_t reset_store(struct device *dev,
>  	zram = dev_to_zram(dev);
>  	bdev = bdget_disk(zram->disk, 0);
>  
> +	if (!bdev)
> +		return -EBUSY;
> +

Oops, Sorry.
I don't think EBUSY is right. How about ENOMEM?

-- 
Kind regards,
Minchan Kim
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