From 97daa028f3f621adff2c4f7b15fe0874e5b5bd6c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 7 Apr 2020 23:40:59 -0700 Subject: KVM: s390: Return last valid slot if approx index is out-of-bounds Return the index of the last valid slot from gfn_to_memslot_approx() if its binary search loop yielded an out-of-bounds index. The index can be out-of-bounds if the specified gfn is less than the base of the lowest memslot (which is also the last valid memslot). Note, the sole caller, kvm_s390_get_cmma(), ensures used_slots is non-zero. Fixes: afdad61615cc3 ("KVM: s390: Fix storage attributes migration with memory slots") Cc: stable@vger.kernel.org # 4.19.x: 0774a964ef56: KVM: Fix out of range accesses to memslots Cc: stable@vger.kernel.org # 4.19.x Signed-off-by: Sean Christopherson Message-Id: <20200408064059.8957-3-sean.j.christopherson@intel.com> Reviewed-by: Cornelia Huck Signed-off-by: Paolo Bonzini --- arch/s390/kvm/kvm-s390.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/s390/kvm/kvm-s390.c') diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 19a81024fe16..5dcf9ff12828 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1939,6 +1939,9 @@ static int gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn) start = slot + 1; } + if (start >= slots->used_slots) + return slots->used_slots - 1; + if (gfn >= memslots[start].base_gfn && gfn < memslots[start].base_gfn + memslots[start].npages) { atomic_set(&slots->lru_slot, start); -- cgit v1.2.3