Revert "Prevent out-of-boundary mem access in ext-inter"

This reverts commit 6a632e2097790595d00d1ed0e14712d46deb8ef7.

This fails to build after the required change was reverted on top of
which this was rebased on submit:
1b6ccfcfa Revert "Fix separation between ext-inter group of expts."

Change-Id: I5fc50bccc019a31386aad35b12fed8402a09a217