From c2cf265d860882b51a200e4a7553c17827f2b730 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Thu, 21 Dec 2017 09:18:22 +0100 Subject: [PATCH] KVM: s390: prevent buffer overrun on memory hotplug during migration We must not go beyond the pre-allocated buffer. This can happen when a new memory slot is added during migration. Reported-by: David Hildenbrand Signed-off-by: Christian Borntraeger Cc: stable@vger.kernel.org # 4.13+ Fixes: 190df4a212a7 (KVM: s390: CMMA tracking, ESSA emulation, migration mode) Reviewed-by: Cornelia Huck Reviewed-by: David Hildenbrand --- arch/s390/kvm/priv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c index 572496c688cc..0714bfa56da0 100644 --- a/arch/s390/kvm/priv.c +++ b/arch/s390/kvm/priv.c @@ -1006,7 +1006,7 @@ static inline int do_essa(struct kvm_vcpu *vcpu, const int orc) cbrlo[entries] = gfn << PAGE_SHIFT; } - if (orc) { + if (orc && gfn < ms->bitmap_size) { /* increment only if we are really flipping the bit to 1 */ if (!test_and_set_bit(gfn, ms->pgste_bitmap)) atomic64_inc(&ms->dirty_pages);