Fix overflow in memory ranges.

Under normal circumstances, it should be impossible to cause this
overflow, but a hostile actor could potentially force it. So fix
an overflow where the offset + length overflows.

Found from the unwinder fuzzer.

Bug: 170307390

Test: Unit tests pass.
Test: Fuzzer error case passes.
Change-Id: I116b86a566c8c0069595f3da30984d6e667e7e4f
2 files changed
tree: 3e164cf5ce86493acdb00997c7801a8524000991
  1. libbacktrace/
  2. libunwindstack/
  3. PREUPLOAD.cfg