* Fix out-of-bounds string read by verifying null-terminator existence
during extraction.
* Fix heap buffer overflow by validating dictionary string lengths
against target shader buffers before copying.
* Fix out-of-bounds array reads by validating chunk-provided lookup
indices against parsed dictionary sizes.
* Fix integer wrapping exploits by replacing pointer addition with
offset subtraction during chunk size verifications.
Add unit tests for these vulerabilities.
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