From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Simek <michal.simek@xilinx.com>
Date: Thu, 22 Aug 2019 08:27:17 +0000
Subject: Re: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table_write()
Message-Id: <ef4d7882-db4a-589a-2aa5-2e329e80fa45@xilinx.com>
List-Id: <kernel-janitors.vger.kernel.org>
References: <20190821071122.GD26957@mwanda>
In-Reply-To: <20190821071122.GD26957@mwanda>
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To: Dan Carpenter <dan.carpenter@oracle.com>, Derek Kiernan <derek.kiernan@xilinx.com>, Dragan Cvetic <dragan.cvetic@xilinx.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, kernel-janitors@vger.kernel.org, Michal Simek <michal.simek@xilinx.com>, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org

On 21. 08. 19 9:11, Dan Carpenter wrote:
> The checking here needs to handle integer overflows because "offset" and
> "len" come from the user.
> 
> Fixes: 20ec628e8007 ("misc: xilinx_sdfec: Add ability to configure LDPC")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  drivers/misc/xilinx_sdfec.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
> index 3fc53d20abf3..0bf3bcc8e1ef 100644
> --- a/drivers/misc/xilinx_sdfec.c
> +++ b/drivers/misc/xilinx_sdfec.c
> @@ -611,7 +611,9 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset,
>  	 * Writes that go beyond the length of
>  	 * Shared Scale(SC) table should fail
>  	 */
> -	if ((XSDFEC_REG_WIDTH_JUMP * (offset + len)) > depth) {
> +	if (offset > depth / XSDFEC_REG_WIDTH_JUMP ||
> +	    len > depth / XSDFEC_REG_WIDTH_JUMP ||
> +	    offset + len > depth / XSDFEC_REG_WIDTH_JUMP) {
>  		dev_dbg(xsdfec->dev, "Write exceeds SC table length");
>  		return -EINVAL;
>  	}
> 

Reviewed-by: Michal Simek <michal.simek@xilinx.com>

Thanks,
Michal