Re: [PATCH] tests/pdx: fix overflow from conversion from page index to address on 32bit

[Jan Beulich <jbeulich@suse.com>]

On 12.03.2026 09:02, Roger Pau Monne wrote:
> When building the PDX test harness as a 32bit executable the page shifts
> done on unsigned long types can overflow.  Instead use pfn_to_paddr(),
> which casts the values to paddr_t previous to doing the shift.
> 
> Fixes: cb50e4033717 ("test/pdx: add PDX compression unit tests")
> Reported-by: Edwin Török <edwin.torok@citrix.com>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>

> --- a/tools/tests/pdx/test-pdx.c
> +++ b/tools/tests/pdx/test-pdx.c
> @@ -208,8 +208,8 @@ int main(int argc, char **argv)
>              if ( !tests[i].ranges[j].start && !tests[i].ranges[j].end )
>                  break;
>  
> -            pfn_pdx_add_region(tests[i].ranges[j].start << PAGE_SHIFT,
> -                               size << PAGE_SHIFT);
> +            pfn_pdx_add_region(pfn_to_paddr(tests[i].ranges[j].start),
> +                               pfn_to_paddr(size));
>          }
>  
>          if ( pfn_pdx_compression_setup(0) != tests[i].compress )
> @@ -233,8 +233,8 @@ int main(int argc, char **argv)
>              if ( !start && !end )
>                  break;
>  
> -            if ( !pdx_is_region_compressible(start << PAGE_SHIFT, 1) ||
> -                 !pdx_is_region_compressible((end - 1) << PAGE_SHIFT, 1) )
> +            if ( !pdx_is_region_compressible(pfn_to_paddr(start), 1) ||
> +                 !pdx_is_region_compressible(pfn_to_paddr(end - 1), 1) )
>              {
>                  printf(
>      "PFN compression invalid, pages %#lx and %#lx should be compressible\n",

Largely unrelated remark, from going through all of the PAGE_SHIFT uses: Isn't
the __LP64__ conditional excluding quite a few too many array elements in
main()'s tests[]?

Jan