Do you need any permission to read data from an sdcard? I found the write permission but nothing for read.
Key here is what you want to read. As mentioned above, you need the permission if you are reading content NOT created by your app. Some devices lets you get away with this also, provided the developer options allow it on the device. But better to include it in the manifest.
If you are only reading what you wrote using the same app, no explicit permission is required.