Fix off-by-one OOB NUL write in GetCertName (classic ASN parser)#10952
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embhorn wants to merge 1 commit into
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Fix off-by-one OOB NUL write in GetCertName (classic ASN parser)#10952embhorn wants to merge 1 commit into
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Pull request overview
Fixes a one-byte out-of-bounds NUL terminator write in the classic ASN.1 parser’s GetCertName() when a Subject/Issuer DN exactly fills the WC_ASN_NAME_MAX buffer, by tightening “too big” checks so exact-fit (no room for '\0') is rejected.
Changes:
- Update
GetCertName()buffer-capacity comparisons from>to>=to ensure space remains for the terminating NUL. - Add a regression test that constructs certificates whose second RDN hits the DN buffer boundary (exact cap vs. one byte under), covering multiple attribute-prefix branches.
- Register the new test in the ASN API test declarations/group list.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
wolfcrypt/src/asn_orig.c |
Tightens DN buffer bounds checks to prevent an exact-fill case from writing the NUL terminator out of bounds. |
tests/api/test_asn.h |
Declares and registers the new DN boundary regression test. |
tests/api/test_asn.c |
Adds test_ParseCert_dnBufferBoundary() to validate boundary behavior across relevant DN attribute branches. |
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Fenrir Automated Review — PR #10952
Scan targets checked: wolfcrypt-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src
No new issues found in the changed files. ✅
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retest this please |
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Description
GetCertName() in the classic ASN.1 parser (asn_orig.c) wrote a 1-byte out-of-bounds NUL terminator when a certificate's Subject or Issuer DN exactly filled the WC_ASN_NAME_MAX-byte cert->subject / cert->issuer buffer.
Fixes zd22171
Testing
test_ParseCert_dnBufferBoundary, which builds certificates whose second RDN lands the name index on exactly the buffer cap.Checklist