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    Subject[PATCH 4.14 38/38] KVM: s390: prevent buffer overrun on memory hotplug during migration
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Christian Borntraeger <borntraeger@de.ibm.com>

    commit c2cf265d860882b51a200e4a7553c17827f2b730 upstream.

    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 <david@redhat.com>
    Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
    Fixes: 190df4a212a7 (KVM: s390: CMMA tracking, ESSA emulation, migration mode)
    Reviewed-by: Cornelia Huck <cohuck@redhat.com>
    Reviewed-by: David Hildenbrand <david@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/s390/kvm/priv.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/arch/s390/kvm/priv.c
    +++ b/arch/s390/kvm/priv.c
    @@ -1009,7 +1009,7 @@ static inline int do_essa(struct kvm_vcp
    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);

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