Re: [PATCH v2] EFI: make for_each_efi_memory_desc_in_map() cope with running on Xen

Matt Fleming
2016-08-16T11:49:17Z

On Mon, 15 Aug, at 09:05:45AM, Jan Beulich wrote:
> While commit 55f1ea15216 ("efi: Fix for_each_efi_memory_desc_in_map()
> for empty memmaps") made an attempt to deal with empty memory maps, it
> didn't address the case where the desc_size field never gets set, as is
> apparently the case when running under Xen.
>
> Reported-by: <lists-Ilq5uHa1fWNWk0Htik3J/w@public.gmane.org>
> Cc: Vitaly Kuznetsov <vkuznets-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Jiri Slaby <jslaby-AlSwsSmVLrQ@public.gmane.org>
> Signed-off-by: Jan Beulich <jbeulich-IBi9RG/b67k@public.gmane.org>
> Tested-by: <lists-Ilq5uHa1fWNWk0Htik3J/w@public.gmane.org>
> ---
> v2: Add comment.
> ---
> include/linux/efi.h | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> --- 4.8-rc2/include/linux/efi.h
> +++ 4.8-rc2-EFI-memdesc-iterator-Xen/include/linux/efi.h
> @@ -946,7 +946,11 @@ extern int efi_memattr_apply_permissions
> /* Iterate through an efi_memory_map */
> #define for_each_efi_memory_desc_in_map(m, md) \
> for ((md) = (m)->map; \
> - ((void *)(md) + (m)->desc_size) <= (m)->map_end; \
> + /* \
> + * Leverage wrapping of the calculation to avoid an infinite \
> + * loop when all three values are zero. \
> + */ \
> + ((void *)(md) + (m)->desc_size - 1) < (m)->map_end; \
> (md) = (void *)(md) + (m)->desc_size)
>

Thanks Jan, applied to the 'urgent' EFI queue and tagged for stable.
I'll send it out this week.