linux-kernel - RE: [PATCH 3/4] misc: xilinx_sdfec: Prevent a divide by zero in xsdfec_reg0

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Date:   Fri, 23 Aug 2019 08:23:54 +0000
From:   Dragan Cvetic <draganc@...inx.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Derek Kiernan <dkiernan@...inx.com>
CC:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Simek <michals@...inx.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: RE: [PATCH 3/4] misc: xilinx_sdfec: Prevent a divide by zero in
 xsdfec_reg0_write()

Hi Dan,

> -----Original Message-----
> From: Dan Carpenter [mailto:dan.carpenter@...cle.com]
> Sent: Wednesday 21 August 2019 08:10
> To: Derek Kiernan <dkiernan@...inx.com>; Dragan Cvetic <draganc@...inx.com>
> Cc: Arnd Bergmann <arnd@...db.de>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>; Michal Simek <michals@...inx.com>;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; kernel-janitors@...r.kernel.org
> Subject: [PATCH 3/4] misc: xilinx_sdfec: Prevent a divide by zero in xsdfec_reg0_write()
> 
> The "psize" value comes from the user so we need to verify that it's
> non-zero before we check if "n % psize" or it will crash.
> 
> Fixes: 20ec628e8007 ("misc: xilinx_sdfec: Add ability to configure LDPC")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
> The parentheses in this condition are a no-op.  They're just confusing.
> Perhaps something else was intended?
> 
>  drivers/misc/xilinx_sdfec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
> index 813b82c59360..3fc53d20abf3 100644
> --- a/drivers/misc/xilinx_sdfec.c
> +++ b/drivers/misc/xilinx_sdfec.c
> @@ -460,7 +460,7 @@ static int xsdfec_reg0_write(struct xsdfec_dev *xsdfec, u32 n, u32 k, u32 psize,
>  {
>  	u32 wdata;
> 
> -	if (n < XSDFEC_REG0_N_MIN || n > XSDFEC_REG0_N_MAX ||
> +	if (n < XSDFEC_REG0_N_MIN || n > XSDFEC_REG0_N_MAX || psize == 0 ||
>  	    (n > XSDFEC_REG0_N_MUL_P * psize) || n <= k || ((n % psize) != 0)) {
>  		dev_dbg(xsdfec->dev, "N value is not in range");
>  		return -EINVAL;
> --
> 2.20.1

Reviewed-by: Dragan Cvetic <dragan.cvetic@...inx.com>

Thanks,
Dragan