KVM: Fix the bitmap range to copy during clear dirty

kvm_dirty_bitmap_bytes() will return the size of the dirty bitmap of
the memslot rather than the size of bitmap passed over from the ioctl.
Here for KVM_CLEAR_DIRTY_LOG we should only copy exactly the size of
bitmap that covers kvm_clear_dirty_log.num_pages.

Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 2a31b9db153530df4aa02dac8c32837bf5f47019
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 53de2f946f9e79f011117aafa6b05a8573e4216c..ad39c57de82d8cd4a6ba3b1c3e884c5d9f3f0b63 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1251,7 +1251,7 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
        if (!dirty_bitmap)
                return -ENOENT;
 
-       n = kvm_dirty_bitmap_bytes(memslot);
+       n = ALIGN(log->num_pages, BITS_PER_LONG) / 8;
 
        if (log->first_page > memslot->npages ||
            log->num_pages > memslot->npages - log->first_page ||