Re: [PATCH v2 06/10] zram: avoid access beyond the zram device

From: Minchan Kim <minchan@kernel.org>
To: Jiang Liu <liuj97@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Nitin Gupta <ngupta@vflare.org>,
	Jerome Marchand <jmarchan@redhat.com>,
	Yijing Wang <wangyijing@huawei.com>,
	Jiang Liu <jiang.liu@huawei.com>,
	devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 06/10] zram: avoid access beyond the zram device
Date: Wed, 5 Jun 2013 15:43:01 +0900	[thread overview]
Message-ID: <20130605064301.GF8732@blaptop> (raw)
In-Reply-To: <1370361968-8764-6-git-send-email-jiang.liu@huawei.com>

On Wed, Jun 05, 2013 at 12:06:04AM +0800, Jiang Liu wrote:
> Function valid_io_request() should verify the entire request doesn't
> exceed the zram device, otherwise it will cause invalid memory access.

Right but you need to explain what invalid memory access is and what's
the result from that to user.

> 
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/staging/zram/zram_drv.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
> index 6a54bb9..1c3974f 100644
> --- a/drivers/staging/zram/zram_drv.c
> +++ b/drivers/staging/zram/zram_drv.c
> @@ -428,6 +428,10 @@ static inline int valid_io_request(struct zram *zram, struct bio *bio)
>  		return 0;
>  	}
>  
> +	if (unlikely((bio->bi_sector << SECTOR_SHIFT) + bio->bi_size >=
> +		     zram->disksize))
> +		return 0;
> +
>  	/* I/O request is valid */
>  	return 1;
>  }
> -- 
> 1.8.1.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Kind regards,
Minchan Kim