From f4cf483e2a1aec2b359347f0a34abd6bf2f208c2 Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Fri, 26 Feb 2021 10:56:38 +0000 Subject: [PATCH] xen/iommu: x86: Don't try to free page tables is the IOMMU is not enabled When using CONFIG_BIGMEM=y, the page_list cannot be accessed whilst it is is unitialized. However, iommu_free_pgtables() will be called even if the domain is not using an IOMMU. Consequently, Xen will try to go through the page list and deference a NULL pointer. Bail out early if the domain is not using an IOMMU. Fixes: 15bc9a1ef51c ("x86/iommu: add common page-table allocator") Signed-off-by: Julien Grall Reviewed-by: Jan Beulich Release-Acked-by: Ian Jackson --- xen/drivers/passthrough/x86/iommu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/xen/drivers/passthrough/x86/iommu.c b/xen/drivers/passthrough/x86/iommu.c index cea1032b3d..58a330e822 100644 --- a/xen/drivers/passthrough/x86/iommu.c +++ b/xen/drivers/passthrough/x86/iommu.c @@ -267,6 +267,9 @@ int iommu_free_pgtables(struct domain *d) struct page_info *pg; unsigned int done = 0; + if ( !is_iommu_enabled(d) ) + return 0; + while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) ) { free_domheap_page(pg); -- 2.30.2