Check ctx extensions before rejecting a TLS1.3 certificate message extension

[aidangarske]

wolfSSL_CTX_UseOCSPStapling() stores status_request on ctx->extensions, and nothing copies it to ssl->extensions. The ClientHello is written from the CTX, so the extension is offered, but the RFC 8446 4.4.2 check in TLSX_Parse() only searched ssl->extensions and killed the server's staple:

Parsing 1836 bytes of cert extensions
Cert-msg extension not offered in CH/CR
SendAlert: 110 unsupported_extension   -> -429

So OCSP stapling over TLS 1.3 fails for any client that uses the CTX-level API. TLS 1.2 takes a different path and is unaffected. TLSX_CheckUnsupportedExtension() already does this ssl-then-ctx lookup; this call site now matches it.

Found by wolfssl-examples ocsp/stapling, which uses the documented CTX API. Currently pointing OCSP testing here till merged

[Copilot]

Pull request overview

Fixes a TLS 1.3 interoperability bug where Certificate message extensions (notably OCSP stapling’s status_request) were incorrectly rejected when the client enabled them via the CTX-level API (ctx->extensions) instead of the SSL-level list (ssl->extensions). This aligns the RFC 8446 §4.4.2 “only accept what was offered” check with existing behavior elsewhere (e.g., TLSX_CheckUnsupportedExtension()), allowing TLS 1.3 OCSP stapling to work for clients using wolfSSL_CTX_UseOCSPStapling().

Changes:

• Extend the TLS 1.3 Certificate-message extension “was it offered?” check to look in ssl->ctx->extensions when not found in ssl->extensions.
• Add a defensive ssl->ctx == NULL guard before dereferencing ssl->ctx->extensions.
• Update the inline comment to document why CTX-level lookup is necessary at this call site.

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[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m4-rsa-only

• FLASH: .text +64 B (+0.0%, 325,184 B / 1,048,576 B, total: 31% used)

gcc-arm-cortex-m7-tls13

• FLASH: .text +64 B (+0.0%, 236,274 B / 262,144 B, total: 90% used)
  No memory changes detected for:
• gcc-arm-cortex-m0plus
• gcc-arm-cortex-m3
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-baremetal
• gcc-arm-cortex-m4-crypto-only
• gcc-arm-cortex-m4-dtls13
• gcc-arm-cortex-m4-min-ecc
• gcc-arm-cortex-m4-openssl-compat
• gcc-arm-cortex-m4-pkcs7
• gcc-arm-cortex-m4-pq
• gcc-arm-cortex-m4-sp-math
• gcc-arm-cortex-m4-tls12
• gcc-arm-cortex-m4-tls13
• gcc-arm-cortex-m7
• gcc-arm-cortex-m7-pq
• linuxkm-pie
• linuxkm-standard
• stm32-sim-stm32h753

[aidangarske]

Jenkins retest this please

[Frauschi]

LGTM