From dc419f0a3752032ab00124dc55609d9231e53128 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 25 Nov 2014 10:07:09 +0100 Subject: [PATCH] x86: tighten page table owner checking in do_mmu_update() MMU_MACHPHYS_UPDATE, not manipulating page tables, shouldn't ignore a bad page table domain being specified. Also pt_owner can't be NULL when reaching the "out" label, so the respective check can be dropped. Signed-off-by: Jan Beulich Acked-by: Tim Deegan Release-Acked-by: Konrad Rzeszutek Wilk --- xen/arch/x86/mm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 3e3353cb48..61b8e776aa 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -3618,6 +3618,11 @@ long do_mmu_update( break; case MMU_MACHPHYS_UPDATE: + if ( unlikely(d != pt_owner) ) + { + rc = -EPERM; + break; + } if ( unlikely(paging_mode_translate(pg_owner)) ) { @@ -3693,7 +3698,7 @@ long do_mmu_update( perfc_add(num_page_updates, i); out: - if ( pt_owner && (pt_owner != d) ) + if ( pt_owner != d ) rcu_unlock_domain(pt_owner); /* Add incremental work we have done to the @done output parameter. */ -- 2.30.2