Change ValidateDer to iterative evaluation#128874
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Since this change doesn't eagerly dive into CONSTRUCTED values, it will change when it encounters a value that gets rejected, but since it doesn't report where the invalid value was found, that doesn't matter.
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Pull request overview
This PR updates DER validation in Internal.Cryptography.Helpers.ValidateDer to use an iterative traversal (explicit stack/queue) instead of recursive descent, preventing StackOverflowException on deeply nested constructed ASN.1 values. It also adds an X509 CertificateRequest regression test that exercises very deep nesting through OtherRequestAttributes.
Changes:
- Rework
Helpers.ValidateDerto iteratively validate nested constructed values (avoids recursion-based stack overflow). - Add a regression test covering both valid and intentionally-invalid, deeply nested
OtherRequestAttributesDER payloads.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/Helpers.cs | Replaces recursive DER validation with iterative processing; introduces an overflow path for deep nesting. |
| src/libraries/System.Security.Cryptography/tests/X509Certificates/CertificateCreation/CertificateRequestApiTests.cs | Adds a theory validating behavior with very deep nesting (and an invalid mutation) in OtherRequestAttributes. |
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
vcsjones
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Jun 2, 2026
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Looks good, some nits that could be addressed.
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Since this change doesn't eagerly dive into CONSTRUCTED values, it will change when it encounters a value that gets rejected, but since it doesn't report where the invalid value was found, that doesn't matter.