Histogram Levels accepts NaN factor

[msg7086]

Analysis attribution: This issue analysis was created by Codex GPT.
The GitHub user who submits this issue does not claim authorship of the analysis.

Finding

• Finding ID: B11-histogram-levels-non-finite-factor
• Status: Reproduced defect
• Severity: Medium
• Affected component: Histogram Levels
• Source location: avs_core/filters/histogram.cpp:137-155

Summary

The factor range check relies on comparisons that NaN bypasses.

Affected Code

optionValid = option.IsFloat();
const double factor = option.AsDblDef(100.0);
if (factor < 0.0 || factor > 100.0) {
  env->ThrowError("Histogram: Levels population clamping must be between 0 and 100%");
}

Correct Behavior

Reject NaN and Infinity before range validation.

Reproduction

Call Histogram(mode="levels", factor=sqrt(-1.0)).

Observed Result

observed: construction succeeds
expected: AvisynthError

Impact

Non-finite configuration reaches histogram arithmetic.

Validation Criteria

NaN and infinities fail; documented finite factor values remain accepted.

Version and Environment

• AviSynthPlus revision: 815780226951f95dfc1fc74f1df90ef98824fcf5
• Platform and compiler: Linux x86_64 / Clang 22 debug
• CPU features used: host-default build.