From d3cfb4b3a680d3e2ddd36f18201d48441f36aea0 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 23 Nov 2021 13:33:14 +0100 Subject: [PATCH] x86/PoD: handle intermediate page orders in p2m_pod_cache_add() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit p2m_pod_decrease_reservation() may pass pages to the function which aren't 4k, 2M, or 1G. Handle all intermediate orders as well, to avoid hitting the BUG() at the switch() statement's "default" case. This is CVE-2021-28708 / part of XSA-388. Fixes: 3c352011c0d3 ("x86/PoD: shorten certain operations on higher order ranges") Signed-off-by: Jan Beulich Reviewed-by: Roger Pau Monné master commit: 8ec13f68e0b026863d23e7f44f252d06478bc809 master date: 2021-11-22 12:27:30 +0000 --- xen/arch/x86/mm/p2m-pod.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c index c14801f5ff..c981200087 100644 --- a/xen/arch/x86/mm/p2m-pod.c +++ b/xen/arch/x86/mm/p2m-pod.c @@ -111,15 +111,13 @@ p2m_pod_cache_add(struct p2m_domain *p2m, /* Then add to the appropriate populate-on-demand list. */ switch ( order ) { - case PAGE_ORDER_1G: - for ( i = 0; i < (1UL << PAGE_ORDER_1G); i += 1UL << PAGE_ORDER_2M ) + case PAGE_ORDER_2M ... PAGE_ORDER_1G: + for ( i = 0; i < (1UL << order); i += 1UL << PAGE_ORDER_2M ) page_list_add_tail(page + i, &p2m->pod.super); break; - case PAGE_ORDER_2M: - page_list_add_tail(page, &p2m->pod.super); - break; - case PAGE_ORDER_4K: - page_list_add_tail(page, &p2m->pod.single); + case PAGE_ORDER_4K ... PAGE_ORDER_2M - 1: + for ( i = 0; i < (1UL << order); i += 1UL << PAGE_ORDER_4K ) + page_list_add_tail(page + i, &p2m->pod.single); break; default: BUG();