Re: [PATCH 1/4] misc: xilinx_sdfec: Fix a couple small information leaks

Michal Simek
2019-08-22T08:14:28Z

Hi Dan,

On 21. 08. 19 9:06, Dan Carpenter wrote:
> These structs have holes in them so we end up disclosing a few bytes of
> uninitialized stack data.
>
> drivers/misc/xilinx_sdfec.c:305 xsdfec_get_status() warn: check that 'status' doesn't leak information (struct has a hole after 'activity')
> drivers/misc/xilinx_sdfec.c:449 xsdfec_get_turbo() warn: check that 'turbo_params' doesn't leak information (struct has a hole after 'scale')

Who is generating these warnings? Is this any new GCC or different tool?
I see that 3byte padding but never seen these warnings.

> We need to zero out the holes with memset().
>
> Fixes: 6bd6a690c2e7 ("misc: xilinx_sdfec: Add stats & status ioctls")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> drivers/misc/xilinx_sdfec.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
> index 912e939dec62..dc1b8b412712 100644
> --- a/drivers/misc/xilinx_sdfec.c
> +++ b/drivers/misc/xilinx_sdfec.c
> @@ -295,6 +295,7 @@ static int xsdfec_get_status(struct xsdfec_dev *xsdfec, void __user *arg)
> struct xsdfec_status status;
> int err;
>
> + memset(&status, 0, sizeof(status));
> spin_lock_irqsave(&xsdfec->error_data_lock, xsdfec->flags);
> status.state = xsdfec->state;
> xsdfec->state_updated = false;
> @@ -440,6 +441,7 @@ static int xsdfec_get_turbo(struct xsdfec_dev *xsdfec, void __user *arg)
> if (xsdfec->config.code == XSDFEC_LDPC_CODE)
> return -EIO;
>
> + memset(&turbo_params, 0, sizeof(turbo_params));
> reg_value = xsdfec_regread(xsdfec, XSDFEC_TURBO_ADDR);
>
> turbo_params.scale = (reg_value & XSDFEC_TURBO_SCALE_MASK) >>
>

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

Thanks,
Michal