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

On 11/13/2013 01:23 PM, Ian Campbell wrote:
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.

Oh right, I will fix it in the next version.

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

Julien Grall

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