Re: [PATCH] powerpc/32: Fix missing NULL pmd check in virt_to_kpte()

[Nick Desaulniers]

Hello ppc friends, did this get picked up into -next yet?

On Thu, Mar 12, 2020 at 8:35 PM Nathan Chancellor
<natechancellor@xxxxxxxxx> wrote:
>
> On Sat, Mar 07, 2020 at 10:09:15AM +0000, Christophe Leroy wrote:
> > Commit 2efc7c085f05 ("powerpc/32: drop get_pteptr()"),
> > replaced get_pteptr() by virt_to_kpte(). But virt_to_kpte() lacks a
> > NULL pmd check and returns an invalid non NULL pointer when there
> > is no page table.
> >
> > Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> > Fixes: 2efc7c085f05 ("powerpc/32: drop get_pteptr()")
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> > ---
> >  arch/powerpc/include/asm/pgtable.h | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> > index b80bfd41828d..b1f1d5339735 100644
> > --- a/arch/powerpc/include/asm/pgtable.h
> > +++ b/arch/powerpc/include/asm/pgtable.h
> > @@ -54,7 +54,9 @@ static inline pmd_t *pmd_ptr_k(unsigned long va)
> >
> >  static inline pte_t *virt_to_kpte(unsigned long vaddr)
> >  {
> > -     return pte_offset_kernel(pmd_ptr_k(vaddr), vaddr);
> > +     pmd_t *pmd = pmd_ptr_k(vaddr);
> > +
> > +     return pmd_none(*pmd) ? NULL : pte_offset_kernel(pmd, vaddr);
> >  }
> >  #endif
> >
> > --
> > 2.25.0
> >
>
> With QEMU 4.2.0, I can confirm this fixes the panic:
>
> Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx>



-- 
Thanks,
~Nick Desaulniers