[PATCH] virtio/virtio_mem: handle a possible NULL as a memcpy parameter

[Peng Hao]

There is a check for vm->sbm.sb_states before, and it should check
it here as well.

Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx>
---
 drivers/virtio/virtio_mem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 96e5a8782769..b6b7c489c8b6 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -592,7 +592,7 @@ static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)
 		return -ENOMEM;
 
 	mutex_lock(&vm->hotplug_mutex);
-	if (new_bitmap)
+	if (vm->sbm.sb_states)
 		memcpy(new_bitmap, vm->sbm.sb_states, old_pages * PAGE_SIZE);
 
 	old_bitmap = vm->sbm.sb_states;
-- 
2.27.0