Re: [ndctl PATCH v2 1/3] cxl/region: fix a dereferecnce after NULL check

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Tue, 23 Aug 2022 01:45:25 -0600
Vishal Verma <vishal.l.verma@intel.com> wrote:

> A NULL check in region_action() implies that 'decoder' might be NULL, but
> later we dereference it during cxl_decoder_foreach(). The NULL check is
> valid because it was the filter result being checked, however, while
> doing this, the original 'decoder' variable was being clobbered.
> 
> Check the filter results independently of the original decoder variable.
> 
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

Typo in patch title.

> ---
>  cxl/region.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/cxl/region.c b/cxl/region.c
> index a30313c..334fcc2 100644
> --- a/cxl/region.c
> +++ b/cxl/region.c
> @@ -686,9 +686,8 @@ static int region_action(int argc, const char **argv, struct cxl_ctx *ctx,
>  			continue;
>  
>  		cxl_decoder_foreach (port, decoder) {
> -			decoder = util_cxl_decoder_filter(decoder,
> -							  param.root_decoder);
> -			if (!decoder)
> +			if (!util_cxl_decoder_filter(decoder,
> +						     param.root_decoder))
>  				continue;
>  			rc = decoder_region_action(p, decoder, action, count);
>  			if (rc)