linux-kernel - Re: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table

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Message-ID: <ef4d7882-db4a-589a-2aa5-2e329e80fa45@xilinx.com>
Date:   Thu, 22 Aug 2019 10:27:17 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Simek <michal.simek@...inx.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in
 xsdfec_table_write()

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@...cle.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@...inx.com>

Thanks,
Michal