harden forcezero and compiler barriers by stenslae · Pull Request #10935 · wolfSSL/wolfssl

stenslae · 2026-07-16T17:36:09Z

Description

Moved wc_ForceZero() and wc_ConstantCompare() from memory.c into wc_port.c so they are always available across builds.
Updated blake2 to use ForceZero() instead of hand rolled volatile loop.
Fixed the portable fallback for WC_BARRIER_DATA() so it escapes the pointer to prevent DSE of stack variables when GNU inline asm isnt available.

A follow up PR will add DSE elimination coverage and regression tests for this PR.

Testing

Cross compiled architectures: x86_64, aarch64, arm32, and riscv64. Statically analyzed and passed forcezero testing.

Checklist

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

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

No new issues found in the changed files. ✅

github-actions · 2026-07-16T18:18:58Z

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Findings are non-blocking.

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

No new issues found in the changed files. ✅

stenslae · 2026-07-17T15:26:27Z

jenkins retest this please

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

No new issues found in the changed files. ✅

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

No new issues found in the changed files. ✅

stenslae · 2026-07-21T18:18:45Z

jenkins retest this please

stenslae · 2026-07-23T16:30:21Z

jenkins retest this please

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-bugs, wolfcrypt-port-bugs, wolfcrypt-rs-bugs, wolfcrypt-src, wolfssl-bugs, wolfssl-src

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

stenslae · 2026-09-09T19:00:25Z

Jenkins retest this please

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

stenslae · 2026-09-21T18:58:37Z

Moved the CI test configs and DSE coverage into a separate pr to keep this one focused on the actual fix

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

stenslae · 2026-09-25T19:40:01Z

Jenkins retest this please

stenslae · 2026-09-28T18:22:47Z

Rebased so changelog messages go into the right place.

Copilot

Copilot review overview

🟡 Changes recommended

Compiler-dependent wipe behavior lacks regression coverage, and changelog entries target an already released version.

Review effort: Balanced
Findings: 1 · 2

Open (3)

Add regression coverage for dead-store elimination in portable buffer wipe · New
Move new API notes to the unreleased changelog section · New
Move implementation fixes to the unreleased changelog section · New

What changed in this PR

Hardens secure memory wiping and compiler barriers across supported builds and architectures.

Changes:

Relocates zeroing/comparison APIs into always-built port code.
Strengthens compiler barriers and fixes ForceZero alignment handling.
Migrates BLAKE2 key cleanup to ForceZero and updates configuration metadata.

File	Description
`.wolfssl_known_macro_extras`	Registers the new barrier compatibility macro.
`ChangeLog.md`	Documents API and hardening changes.
`wolfssl/wolfcrypt/wc_port.h`	Defines APIs, barriers, and architecture fences.
`wolfssl/wolfcrypt/settings.h`	Preserves ForceZero for BLAKE2 and Argon2.
`wolfssl/wolfcrypt/memory.h`	Removes relocated declarations.
`wolfssl/wolfcrypt/blake2-impl.h`	Removes the custom zeroing helper.
`wolfcrypt/src/wc_port.c`	Hosts exported APIs and portable barrier sink.
`wolfcrypt/src/misc.c`	Fixes short-buffer alignment handling.
`wolfcrypt/src/memory.c`	Removes relocated implementations.
`wolfcrypt/src/blake2s.c`	Uses ForceZero for key cleanup.
`wolfcrypt/src/blake2b.c`	Uses ForceZero for key cleanup.

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philljj · 2026-09-30T15:39:39Z

These two PRs are going to collide with same changes:

misc: reject a negative length in ConstantCompare() #11561

Copilot

🟡 Changes recommended

The Arm Compiler 5 path still permits dead-store elimination, and the security hardening lacks regression coverage.

2 open findings

3 resolved since last review

🧠 Review effort: Balanced

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs
Coverage: 2 of 2 in-scope changed file(s) opened by the reviewer

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

Review tier: Lite

Copilot

🟡 Changes recommended

The security guarantee lacks permanent DSE/LTO regression coverage, and the changelog misdocuments armcc5 behavior.

2 open findings

2 resolved since last review

🧠 Review effort: Balanced

Copilot

🟡 Changes recommended

The security and build regressions being fixed need automated coverage in this pull request.

1 open finding

Add regression tests for memory-less and optimized portable barrier wipes · New

2 resolved since last review

🧠 Review effort: Balanced

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs
Coverage: 1 of 1 in-scope changed file(s) opened by the reviewer

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

Review tier: Lite

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: none
Unchanged since last review (not re-run): wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

Review tier: Lite

Copilot

🔵 Needs a closer look

Security-sensitive, compiler-specific barrier behavior lacks the planned regression and DSE coverage.

0 open findings

1 resolved since last review

Add regression tests for memory-less and optimized portable barrier wipes

🧠 Review effort: Balanced

julek-wolfssl · 2026-10-21T19:25:11Z

Once #11809 goes in the changes on this file will be redundant.

Both compilers accept -std=c99, so a C99 build selected the WOLF_C99 arm and expanded to __asm__, a keyword neither assembler dialect takes.

Without it the compiler may keep memory in registers across the fence, so the fence ordered the CPU but not the code generator.

XFENCE() is a macro, so TUs outside the library expand it and need the symbol linkable; WOLFSSL_TEST_VIS marks it internal without hiding it.

(void)(ptr) escaped nothing, so ForceZero() on a non-escaped stack local was still dead-store eliminated on every build without GNU inline asm.

memory.c is excluded from some builds, which left the two exported wrappers undefined; wc_port.c is always compiled.

The one-off byte-at-a-time helper bypassed the barrier-hardened wipe path every other part of wolfCrypt goes through.

stenslae · 2026-10-23T19:24:54Z

claude @review

Copilot

🔵 Needs a closer look

The short-buffer alignment correction remains missing, and security-critical compiler barrier behavior needs final cross-toolchain validation.

1 open issue

Guard ForceZero word-pointer conversion for short misaligned buffers · New

_{Review effort: Balanced}

wolfSSL-Fenrir-bot

Fenrir Automated Review — PR #10935

Scan targets checked: wolfcrypt-src, wolfcrypt-bugs, wolfssl-src, wolfssl-bugs
Not reviewed (no scan target covers them): .wolfssl_known_macro_extras, ChangeLog.md
Coverage: 3 of 8 in-scope changed file(s) opened by the reviewer; not opened: wolfcrypt/src/blake2b.c, wolfcrypt/src/blake2s.c, wolfcrypt/src/memory.c, wolfssl/wolfcrypt/blake2-impl.h, wolfssl/wolfcrypt/memory.h

Fenrir result: Approved ✅

No new issues found in the changed files.

Advisory only — this automated result does not count as a GitHub approval.

Review tier: Lite

stenslae · 2026-10-28T22:14:18Z

Removed xfence barriers to keep this pr more focused.

stenslae requested a review from wolfSSL-Fenrir-bot July 16, 2026 17:36

stenslae self-assigned this Jul 16, 2026

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stenslae force-pushed the fix/wcForceZero branch from fdce988 to c0a7910 Compare July 16, 2026 17:58

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Comment thread wolfssl/wolfcrypt/wc_port.h Outdated

stenslae commented Jul 16, 2026

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stenslae force-pushed the fix/wcForceZero branch from c0a7910 to 69e535e Compare July 16, 2026 19:01

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stenslae force-pushed the fix/wcForceZero branch from 69e535e to 6fcdbd1 Compare July 20, 2026 16:41

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stenslae force-pushed the fix/wcForceZero branch from 6fcdbd1 to b371392 Compare July 20, 2026 18:12

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stenslae force-pushed the fix/wcForceZero branch 2 times, most recently from 1844d19 to 6bf96b1 Compare July 20, 2026 20:37

stenslae requested a review from wolfSSL-Fenrir-bot July 20, 2026 20:50

stenslae force-pushed the fix/wcForceZero branch from 6bf96b1 to 74486d3 Compare July 20, 2026 21:42

stenslae assigned wolfSSL-Bot Jul 21, 2026

stenslae force-pushed the fix/wcForceZero branch from 74486d3 to 84e4744 Compare July 21, 2026 19:56

stenslae requested review from wolfSSL-Fenrir-bot and removed request for wolfSSL-Fenrir-bot July 23, 2026 17:50

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stenslae mentioned this pull request Sep 28, 2026

misc: reject a negative length in ConstantCompare() #11561

Open

2 of 4 tasks

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julek-wolfssl requested changes Oct 21, 2026

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Emma Stensland added 6 commits October 23, 2026 13:17

xasm: check IAR and KEIL before WOLF_C99 in XASM_VOLATILE()

ea8b1ae

Both compilers accept -std=c99, so a C99 build selected the WOLF_C99 arm and expanded to __asm__, a keyword neither assembler dialect takes.

xfence: give every XFENCE() arm a memory clobber

b173e5e

Without it the compiler may keep memory in registers across the fence, so the fence ordered the CPU but not the code generator.

armasm: rename aarch64_use_sb to wc_aarch64_use_sb

a279cbd

XFENCE() is a macro, so TUs outside the library expand it and need the symbol linkable; WOLFSSL_TEST_VIS marks it internal without hiding it.

barrier: make the portable WC_BARRIER_DATA() arm escape the pointer

347337d

(void)(ptr) escaped nothing, so ForceZero() on a non-escaped stack local was still dead-store eliminated on every build without GNU inline asm.

wc_port: move wc_ForceZero() and wc_ConstantCompare() out of memory.c

03de233

memory.c is excluded from some builds, which left the two exported wrappers undefined; wc_port.c is always compiled.

blake2: zeroize with ForceZero() instead of secure_zero_memory()

c04f723

The one-off byte-at-a-time helper bypassed the barrier-hardened wipe path every other part of wolfCrypt goes through.

Copilot AI reviewed Oct 23, 2026

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Comment thread wolfcrypt/src/wc_port.c

wolfSSL-Fenrir-bot reviewed Oct 23, 2026

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philljj mentioned this pull request Oct 25, 2026

Validate peer host keys and DH values in KEX wolfSSL/wolfssh#1320

Merged

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