Type fix in mldsa

[manastasova]

Change types uint32_t t0, t1; to int32_t t0, t1; due to potential overflow in if (t0 < 9){a[ctr++] = 4 - t0;} causing cbmc proofs to fail.

Issues:

From pq-code-package/mldsa-native#86.

Description of changes:

The output array is of type int32_t* a, thus, uint32_t aux values t0, t1 cause cbmc proofs to fail due to potential overflow.

Testing:

./crypto/crypto_test

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[hanno-becker]

@manastasova Why not include an explicit cast here prior to 2 - t_i and 4 - t_i? The computation of t0,t1 is unsigned, I think, and you would want CBMC to check that it does not underflow.

This PR should wait until the corresponding PR pq-code-package/mldsa-native#86 is merged.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.75%. Comparing base (54453b4) to head (38991b5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2308      +/-   ##
==========================================
- Coverage   78.75%   78.75%   -0.01%     
==========================================
  Files         616      616              
  Lines      107650   107649       -1     
  Branches    15303    15300       -3     
==========================================
- Hits        84777    84776       -1     
+ Misses      22219    22218       -1     
- Partials      654      655       +1     

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