Re: [Xen-devel] [PATCH] xen/x86: Annotate deliberate fallthrough cases from XSA-154

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.02.16 at 13:26, <andrew.cooper3@xxxxxxxxxx> wrote:
> Coverity objects otherwise.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> ---
>  xen/arch/x86/mm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
> index a05edc3..0bff7dd 100644
> --- a/xen/arch/x86/mm.c
> +++ b/xen/arch/x86/mm.c
> @@ -924,10 +924,15 @@ get_page_from_l1e(
>              {
>              case 0:
>                  break;
> +
>              case 1:
>                  if ( is_hardware_domain(l1e_owner) )
> +                {
> +                    /* Fallthrough. */
>              case -1:
>                      return 0;
> +                }
> +                /* Fallthrough. */
>              default:

This second fall-through is actually a bug (luckily noticable only
on debug builds).

I'll commit the patch suitably adjusted, albeit I have a hard time
seeing how

            case 1:
                if ( is_hardware_domain(l1e_owner) )
            case -1:

cannot be seen as obviously deliberate. Or did Coverity perhaps
only complain about the second, indeed buggy one?

Jan


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