Fix various memory errors

There were a few memory errors while restoring a backup via adb (created
using `adb backup --twrp`).
On my device (S5 mini) it resulted in this error message:

  FORTIFY: strlen: prevented read past end of buffer

This commit fixes this issue and a few other potential issues.

Change-Id: I5022c94c961217238b3fefec0b2c4b8c6fa26ec7