RE: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table_write()

[Dragan Cvetic]

Hi Dan,


> -----Original Message-----
> From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx]
> Sent: Wednesday 21 August 2019 08:11
> To: Derek Kiernan <dkiernan@xxxxxxxxxx>; Dragan Cvetic <draganc@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; kernel-janitors@xxxxxxxxxxxxxxx
> Subject: [PATCH 4/4] misc: xilinx_sdfec: Prevent integer overflow in xsdfec_table_write()
> 
> The checking here needs to handle integer overflows because "offset" and
> "len" come from the user.

Good catch, thanks.

> 
> Fixes: 20ec628e8007 ("misc: xilinx_sdfec: Add ability to configure LDPC")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
>  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;
>  	}
> --
> 2.20.1

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

Thanks 
Dragan