Re: [Xen-devel] [PATCH V2] xen: Check if the range is valid in init_domheap_pages

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-11-13 at 13:15 +0000, Julien Grall wrote:
> On ARM, when an initrd is given to xen by U-boot, it will reserve the memory 
> in
> the device tree.
> In this case, when xen decides to free unused memory, dt_unreserved_regions
> will call init_domheap_pages with the start and the end of range equals. But
> the latter assumes that (start > end), if not Xen will hang because the
> number of pages is equals to (unsigned)-1.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> 
> ---
>     Changes in v2:
>         - Change commit title
>         - Move the check in init_domheap_pages
> ---
>  xen/common/page_alloc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 4c17fbd..10f67a1 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -1429,6 +1429,9 @@ void init_domheap_pages(paddr_t ps, paddr_t pe)
>      smfn = round_pgup(ps) >> PAGE_SHIFT;
>      emfn = round_pgdown(pe) >> PAGE_SHIFT;
>  
> +    if ( smfn <= emfn )

You've got this backwards I think.

> +        return;
> +
>      init_heap_pages(mfn_to_page(smfn), emfn - smfn);
>  }
>  



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