fix(avm)!: de-risk memory injection attacks

[jeanmon]

Linear issue AVM-180

[sirasistant]

to radix mem refactor looks good

[AztecBot]

Flakey Tests

🤖 says: This CI run detected 3 tests that failed, but were tolerated due to a .test_patterns.yml entry.

\033FLAKED\033 (8;;http://ci.aztec-labs.com/a191e521d701581e�a191e521d701581e8;;�):  yarn-project/end-to-end/scripts/run_test.sh simple src/e2e_epochs/epochs_invalidate_block.parallel.test.ts "committee member invalidates a block if proposer does not come through" (96s) (code: 1) group:e2e-p2p-epoch-flakes (\033jeanmon\033: Fix unit test)
\033FLAKED\033 (8;;http://ci.aztec-labs.com/230043c72f6eb6fb�230043c72f6eb6fb8;;�):  yarn-project/end-to-end/scripts/run_test.sh simple src/e2e_p2p/multiple_validators_sentinel.parallel.test.ts "collects attestations for validators in proposer node when block is not published" (113s) (code: 1) group:e2e-p2p-epoch-flakes (\033jeanmon\033: Fix unit test)
\033FLAKED\033 (8;;http://ci.aztec-labs.com/63c8e76f15869c4e�63c8e76f15869c4e8;;�):  yarn-project/end-to-end/scripts/run_test.sh simple src/e2e_epochs/epochs_invalidate_block.parallel.test.ts "proposer invalidates multiple blocks" (603s) (code: 124) group:e2e-p2p-epoch-flakes (\033jeanmon\033: Fix unit test)

[IlyasRidhuan]

Nice job looks great!

[IlyasRidhuan]

But does #[LAST_HAS_SEL_ON] only guarantee it because there exists a sel' from #[TRACE_CONTINUITY]? So sel cannot be activated on the first row (which means latch can't either)

[jeanmon]

This does not follow from trace continuity. It follows from sel being shifted and therefore cannot be active on the first row (precomputed.first_row == 1). From #[LAST_HAS_SEL_ON], we have sel == 0 implies last == 0 and therefore last is mutually exclusive to precomputed.first_row.

We employed this reasoning many times and I might have been concise here due to habit of it.

[IlyasRidhuan]

Gotcha, there are 2 instance of sel' in the trace, in #[TRACE_CONTINUITY] and in #[START_AFTER_LATCH]