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Validate NumStates and negative Start state in VectorFstImpl::Read. - #346
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…ad`. `VectorFstImpl::Read` previously passed `hdr.NumStates()` directly to `ReserveStates(size_t)` whenever `hdr.NumStates() != kNoStateId`, and only checked `impl->Start() >= state` after reading states. As a result: - A negative `hdr.NumStates()` other than `kNoStateId` (e.g., `-2`) converted to a huge `size_t` in `ReserveStates` and aborted, and a huge positive `hdr.NumStates()` in a corrupt or truncated header attempted an unbounded upfront allocation before reading the first state. - A negative start state `< kNoStateId` (e.g., `-2`) passed the `impl->Start() != kNoStateId && impl->Start() >= state` check. Reject `hdr.NumStates() < 0 || hdr.NumStates() > kMaxStates` (when `!= kNoStateId`), cap the upfront `ReserveStates` call to `kMaxReserveStates`, and reject `impl->Start() < 0` in the start-state range check (matching `ConstFstImpl::Read` and `CompactArcStore::Read`). Add unit tests in `fst_limits_test.cc`. PiperOrigin-RevId: 995131897
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Validate
NumStatesand negativeStartstate inVectorFstImpl::Read.VectorFstImpl::Readpreviously passedhdr.NumStates()directly toReserveStates(size_t)wheneverhdr.NumStates() != kNoStateId, and only checkedimpl->Start() >= stateafter reading states. As a result:hdr.NumStates()other thankNoStateId(e.g.,-2) converted to a hugesize_tinReserveStatesand aborted, and a huge positivehdr.NumStates()in a corrupt or truncated header attempted an unbounded upfront allocation before reading the first state.< kNoStateId(e.g.,-2) passed theimpl->Start() != kNoStateId && impl->Start() >= statecheck.Reject
hdr.NumStates() < 0 || hdr.NumStates() > kMaxStates(when!= kNoStateId), cap the upfrontReserveStatescall tokMaxReserveStates, and rejectimpl->Start() < 0in the start-state range check (matchingConstFstImpl::ReadandCompactArcStore::Read). Add unit tests infst_limits_test.cc.