Check SHE field widths in the software path only

[night1rider]

A crypto callback builds the SHE messages itself and may use its own wider key numbering, so the software packing limits must not reject its values.

[Copilot]

Pull request overview

This PR adjusts SHE message generation so packed-field width checks (counter/flags/key IDs) are enforced only on the software packing path, allowing crypto-callback implementations (e.g., secure elements/HSMs) to accept wider logical key numbering without being rejected up-front.

Changes:

• Moved packed-field width validation in wc_SHE_GenerateM1M2M3() to occur only after the crypto-callback attempt (i.e., only for software path).
• Moved packed-field width validation in wc_SHE_GenerateM4M5() to occur only after the crypto-callback attempt (i.e., only for software path).

Suppressed comments (2)

wolfcrypt/src/wc_she.c:705

• As with M1/M2/M3 generation, the callback path can now accept key IDs beyond WC_SHE_KEY_ID_MAX, but the public header docs describe authKeyId/targetKeyId as 4-bit slot IDs. Consider updating the API documentation to clarify that the software path enforces packed-field widths, while callbacks may use their own key numbering/mapping.

    /* Only the software path packs these into M4, so the widths are
     * checked here.  A callback may use its own key numbering. */
    if (counter > WC_SHE_COUNTER_MAX ||

wolfcrypt/src/wc_she.c:708

• There are existing tests that assert BAD_FUNC_ARG for out-of-range packed field widths on the software path, but no test appears to validate that the callback path bypasses these width checks (e.g., allowing authKeyId/targetKeyId > WC_SHE_KEY_ID_MAX when the callback succeeds). Adding a callback-path regression test would help ensure this behavioral contract remains intact.

    if (counter > WC_SHE_COUNTER_MAX ||
        authKeyId > WC_SHE_KEY_ID_MAX || targetKeyId > WC_SHE_KEY_ID_MAX) {
        return BAD_FUNC_ARG;
    }

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[wolfSSL-Bot]

Can one of the admins verify this patch?

[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

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #11279

Scan targets checked: wolfcrypt-bugs, wolfcrypt-src

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.

Review comment dealt with