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Fix things found using ZeroPath #437

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Merged
dgarske merged 2 commits into from
Oct 22, 2025
Merged

Fix things found using ZeroPath #437

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ae73063
Enforce TPM response HMAC length checks
LinuxJedi Oct 21, 2025
4f6282b
Validate GetProductInfo payload length
LinuxJedi Oct 21, 2025
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26 changes: 22 additions & 4 deletions src/tpm2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -332,10 +332,21 @@ static int TPM2_ResponseProcess(TPM2_CTX* ctx, TPM2_Packet* packet,
}

#if !defined(WOLFTPM2_NO_WOLFCRYPT) && !defined(NO_HMAC)
if (authRsp.hmac.size > 0) {
if (TPM2_IS_HMAC_SESSION(session->sessionHandle) ||
TPM2_IS_POLICY_SESSION(session->sessionHandle))
{
UINT16 expectedHmacSz = TPM2_GetHashDigestSize(session->authHash);
TPM2B_DIGEST hash;
TPM2B_AUTH hmac;

if (expectedHmacSz == 0 || authRsp.hmac.size != expectedHmacSz) {
#ifdef DEBUG_WOLFTPM
printf("Response HMAC size mismatch! expected=%u got=%u\n",
expectedHmacSz, authRsp.hmac.size);
#endif
return TPM_RC_HMAC;
}

/* calculate "rpHash" hash for command code and parameters */
rc = TPM2_CalcRpHash(session->authHash, cmdCode, param, paramSz,
&hash);
Expand Down Expand Up @@ -5472,9 +5483,16 @@ TPM_RC TPM2_GetProductInfo(uint8_t* info, uint16_t size)
*/

/* start of product info starts at byte 26 */
if (size > packet.size - 26)
size = packet.size - 26;
XMEMCPY(info, &packet.buf[25], size);
if (packet.size <= 26) {
rc = TPM_RC_SIZE;
}
else if (size > 0) {
size_t payloadSz = (size_t)(packet.size - 26);
if (payloadSz > (size_t)size) {
payloadSz = (size_t)size;
}
XMEMCPY(info, &packet.buf[25], payloadSz);
}
}
TPM2_ReleaseLock(ctx);
}
Expand Down