Commit 97daa028 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini

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: afdad616 ("KVM: s390: Fix storage attributes migration with memory slots")
Cc: stable@vger.kernel.org # 4.19.x: 0774a964: KVM: Fix out of range accesses to memslots
Cc: stable@vger.kernel.org # 4.19.x
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200408064059.8957-3-sean.j.christopherson@intel.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b6467ab1
...@@ -1939,6 +1939,9 @@ static int gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn) ...@@ -1939,6 +1939,9 @@ static int gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn)
start = slot + 1; start = slot + 1;
} }
if (start >= slots->used_slots)
return slots->used_slots - 1;
if (gfn >= memslots[start].base_gfn && if (gfn >= memslots[start].base_gfn &&
gfn < memslots[start].base_gfn + memslots[start].npages) { gfn < memslots[start].base_gfn + memslots[start].npages) {
atomic_set(&slots->lru_slot, start); atomic_set(&slots->lru_slot, start);
......
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