android: binder: fixup crash introduced by moving buffer hdr

Fix crash introduced by 74310e06be4d74dcf67cd108366710dee5c576d5
(android: binder: Move buffer out of area shared with user space)
when close is called after open without mmap in between.

Reported-by: kernel test robot <fengguang.wu@intel.com>
Fixes: 74310e06be4d ("android: binder: Move buffer out of area shared with user space")
Signed-off-by: Sherry Yang <sherryy@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder_alloc.c

@@ -713,7 +713,6 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 	}
 
 	buffer->data = alloc->buffer;
-	INIT_LIST_HEAD(&alloc->buffers);
 	list_add(&buffer->entry, &alloc->buffers);
 	buffer->free = 1;
 	binder_insert_free_buffer(alloc, buffer);
@@ -972,6 +971,7 @@ void binder_alloc_init(struct binder_alloc *alloc)
 	alloc->tsk = current->group_leader;
 	alloc->pid = current->group_leader->pid;
 	mutex_init(&alloc->mutex);
+	INIT_LIST_HEAD(&alloc->buffers);
 }
 
 void binder_alloc_shrinker_init(void)