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

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Mar 12, 2026 at 09:25:12AM +0100, Jan Beulich wrote:
> 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@xxxxxxxxxx>
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> > --- 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[]?

Hm, I think so.  Will send a separate fix for that however.

Thanks, Roger.