Fix multiple issues with WOLFSSL_CHECK_SIG_FAULTS + HAVE_PK_CALLBACKS.

[kareem-wolfssl]

Description

Fixes zd#22213
Fixes NULL deref since ssl->buffers.key is expected to be NULL when using WOLFSSL_CHECK_SIG_FAULTS + HAVE_PK_CALLBACKS.
Fixes Sm2wSm3Verify call to match the earlier Sm2wSm3Sign call.

Testing

Built in tests

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[Copilot]

Pull request overview

This PR fixes fault-hardening signature verification paths when WOLFSSL_CHECK_SIG_FAULTS is enabled alongside HAVE_PK_CALLBACKS, avoiding NULL dereferences when ssl->buffers.key is intentionally absent, and corrects the SM2/SM3 verify call to match the signing input.

Changes:

• Guard PK-callback key-buffer access (ssl->buffers.key) in TLS 1.3 and TLS 1.2 fault-check verification paths.
• Align TLS 1.2 SM2/SM3 verification with the SM2/SM3 signing input (verify over handshake messages, not the digest).
• Expand CI coverage by adding faultharden-enabled configurations to existing GitHub Actions workflows.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/tls13.c	Prevents NULL dereference when building PK-callback key buffer info for fault-check ECC verify in TLS 1.3.
src/internal.c	Fixes NULL deref for PK-callback key buffer info in multiple TLS 1.2 fault-check verify sites and corrects SM2/SM3 verify input to match signing.
.github/workflows/wolfsm.yml	Adds an SM-focused faultharden CI configuration.
.github/workflows/os-check.yml	Adds an all-config faultharden CI configuration.

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[github-actions]

MemBrowse Memory Report

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-rsa-only
• 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
• gcc-arm-cortex-m7-tls13
• linuxkm-pie
• linuxkm-standard
• stm32-sim-stm32h753

[Frauschi]

🐺 Skoll Code Review

Overall recommendation: APPROVE
Findings: 4 total — 4 posted, 0 skipped

Posted findings

• [Medium] New sm-faultharden CI config omits PK callbacks, so the SM2 + HAVE_PK_CALLBACKS code this PR fixes is still never compiled — .github/workflows/wolfsm.yml:101
• [Medium] Fault check still runs without usable key material when the private key is held by a PK callback, so the handshake fails — src/internal.c:38600
• [Medium] No test exercises the NULL private-key scenario the PR fixes; CI additions give compile coverage only — .github/workflows/os-check.yml:168
• [Low] Dual-algorithm alt-key site left with the unguarded dereference pattern — src/tls13.c:10727

Review generated by Skoll via Claude/Codex

[Frauschi]

Three CI notes, from having built these combinations while chasing a related async NULL deref in EccVerify().

1. The all-faultharden entry needs to move on rebase. It is currently added to the heredoc in .github/workflows/os-check.yml, but #11036 moved that config list out to .github/configs/os-check-linux.json, so the workflow no longer reads it from the YAML. The entry itself is good, it just lands in a file that no longer holds the list. Same shape as before, one entry per line in the JSON file.

2. Offering a second entry, if you want it in the same PR. TEST_PK_PRIVKEY is what makes examples/client.c and examples/server.c leave the private key to the PK callback, so ssl->buffers.key stays NULL, which is the state this PR fixes the handling of. Nothing under .github/ defines it today, so scripts/pkcallbacks.test always runs with the key loaded and never reaches those branches.

{"name": "pkcallbacks-testprivkey", "minutes": 1.5,
 "comment": "TEST_PK_PRIVKEY makes the examples leave the private key to the PK callback, so ssl->buffers.key stays NULL. Without it scripts/pkcallbacks.test always runs with the key loaded and never reaches those branches",
 "configure": ["--enable-pkcallbacks", "CPPFLAGS=-DTEST_PK_PRIVKEY"]}

Verified locally with the CFLAGS the workflow applies at make time: it configures, builds without warnings, and scripts/pkcallbacks.test passes rather than skipping.

It has to stay separate from all-faultharden rather than being folded into it. The two together do not currently complete a handshake: the fault check hands the verify callback a zero key size and myEccVerify() in wolfssl/test.h rejects it with -173, so a combined entry would fail. That looks like a real product gap rather than anything this PR introduces.

3. sm-faultharden in wolfsm.yml configures Public Key Callbacks: no. Building master with exactly those flags catches Sm3wSm2Verify being undeclared, but the sibling DerBuffer* to buffer* break in internal.c sits inside #ifdef HAVE_PK_CALLBACKS and slips through. Adding --enable-pkcallbacks to that entry covers both.

[kareem-wolfssl]

Retest this please