Re: [PATCH v14 08/16] cxl: Reject overflowing HDM decoder ranges

[Dave Jiang]

On 10/1/26 2:22 AM, Srirangan Madhavan wrote:
> An HDM decoder with a nonzero size can report a base and size whose end
> address wraps the 64-bit address space. Reject that programming before
> publishing the decoder range, so enumeration and later reset handling
> cannot use the wrapped range.
> 
> Use check_add_overflow() for nonzero ranges. Preserve the existing
> empty-range representation for zero-size decoders.

Why split this out instead of just introduce it when the function is introduced in the previous patch?

DJ

> 
> Signed-off-by: Srirangan Madhavan <smadhavan@xxxxxxxxxx>
> ---
>  drivers/cxl/core/resource.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c
> index 8dfeb12de8c9..8d2fbc49a06f 100644
> --- a/drivers/cxl/core/resource.c
> +++ b/drivers/cxl/core/resource.c
> @@ -115,16 +115,21 @@ int cxl_hdm_unpack_decoder(struct cxl_decoder_settings *settings, int id,
>  	int interleave_ways;
>  	unsigned long flags = 0;
>  	struct range hpa_range;
> +	u64 end;
>  	int rc;
>  
>  	if (!committed)
>  		size = 0;
>  	if (base == U64_MAX || size == U64_MAX)
>  		return -ENXIO;
> +	if (size && check_add_overflow(base, size - 1, &end))
> +		return -ENXIO;
> +	if (!size)
> +		end = base - 1;
>  
>  	hpa_range = (struct range) {
>  		.start = base,
> -		.end = base + size - 1,
> +		.end = end,
>  	};
>  
>  	if (committed) {