Re: [PATCH 2/2] avoid dereference of null pointer

[Samuel Thibault]

Marin Ramesa, le Sun 10 Nov 2013 16:46:30 +0100, a écrit :
> Check to see if pte is a null pointer and perform dereference only
> if that is not the case.
> 
> * i386/intel/pmap.c (pte): Check if it is a null pointer.

Well, it can never be null, since earlier in the code we see the pv_h
pointing to a map which has the physical page mapped somewhere.

> ---
>  i386/intel/pmap.c | 5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c
> index c1eca6e..283992e 100644
> --- a/i386/intel/pmap.c
> +++ b/i386/intel/pmap.c
> @@ -1567,8 +1567,9 @@ void pmap_page_protect(phys, prot)
>                   /*
>                    * Remove the mapping, collecting any modify bits.
>                    */
> -                 if (*pte & INTEL_PTE_WIRED)
> -                     panic("pmap_remove_all removing a wired page");
> +                     if (pte != NULL)
> +                             if (*pte & INTEL_PTE_WIRED)
> +                                     panic("pmap_remove_all removing a wired 
> page");
>  
>                   {
>                       register int    i = ptes_per_vm_page;
> -- 
> 1.8.1.4
> 
> 

-- 
Samuel
<N> M.  MIMRAM  Samuel Antonin
<N> en voila un qui etait predestiné
 -+- #ens-mim - Quelles gueules qu'ils ont les ptits nouveaux ? -+-