Hi Jan,
On 17/02/2021 14:54, Jan Beulich wrote:
On 17.02.2021 15:24, Julien Grall wrote:
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -267,6 +267,15 @@ int iommu_free_pgtables(struct domain *d)
struct page_info *pg;
unsigned int done = 0;
+ if ( !is_iommu_enabled(d) )
+ return 0;
+
+ /*
+ * Pages will be moved to the free list below. So we want to
+ * clear the root page-table to avoid any potential use after-free.
+ */
+ hd->platform_ops->clear_root_pgtable(d);
Taking amd_iommu_alloc_root() as example, is this really correct
prior to what is now patch 2?
Yes, there are no more use-after-free...
What guarantees a new root table
won't get allocated subsequently?
It doesn't prevent root table allocation. I view the two as distincts
issues, hence the two patches.
Cheers,
--
Julien Grall
