Re: [PATCH] ASoC: Intel: Skylake: Fix available clock counter incrementation

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 2/24/20 6:52 AM, Amadeusz Sławiński wrote:
> Incrementation of avail_clk_cnt was incorrectly moved to error path. Put
> it back to success path.
> 
> Fixes: 6ee927f2f01466 ('ASoC: Intel: Skylake: Fix NULL ptr dereference when unloading clk dev')
> Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
> ---
>   sound/soc/intel/skylake/skl-ssp-clk.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/soc/intel/skylake/skl-ssp-clk.c b/sound/soc/intel/skylake/skl-ssp-clk.c
> index 1c0e5226cb5b..bd43885f3805 100644
> --- a/sound/soc/intel/skylake/skl-ssp-clk.c
> +++ b/sound/soc/intel/skylake/skl-ssp-clk.c
> @@ -384,9 +384,11 @@ static int skl_clk_dev_probe(struct platform_device *pdev)
>   				&clks[i], clk_pdata, i);
>   
>   		if (IS_ERR(data->clk[data->avail_clk_cnt])) {
> -			ret = PTR_ERR(data->clk[data->avail_clk_cnt++]);
> +			ret = PTR_ERR(data->clk[data->avail_clk_cnt]);

Are you sure?

If you start with avail_clk_cnt set to zero, the error handling will 
decrement and access offset -1

static void unregister_src_clk(struct skl_clk_data *dclk)
{
      while (dclk->avail_clk_cnt--)
          clkdev_drop(dclk->clk[dclk->avail_clk_cnt]->lookup); <<< oob 
access with offset -1
}

>   			goto err_unreg_skl_clk;
>   		}
> +
> +		data->avail_clk_cnt++;
>   	}
>   
>   	platform_set_drvdata(pdev, data);
>