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Add missing ForceZero calls #9885

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Merged
douzzer merged 1 commit into from
Mar 11, 2026
Merged

Add missing ForceZero calls #9885

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68 changes: 52 additions & 16 deletions src/keys.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,12 @@
#include <stdio.h>
#endif
#endif
#ifdef NO_INLINE
#include <wolfssl/wolfcrypt/misc.h>
#else
#define WOLFSSL_MISC_INCLUDED
#include <wolfcrypt/src/misc.c>
#endif

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#if defined(WOLFSSL_RENESAS_FSPSM_TLS) || defined(WOLFSSL_RENESAS_TSIP_TLS)
#include <wolfssl/wolfcrypt/port/Renesas/renesas_cmn.h>
Expand Down Expand Up @@ -3902,6 +3908,7 @@ int DeriveKeys(WOLFSSL* ssl)
return MEMORY_E;
}
#endif

XMEMSET(shaOutput, 0, WC_SHA_DIGEST_SIZE);
ret = wc_InitMd5(md5);
if (ret == 0) {
Expand Down Expand Up @@ -3948,6 +3955,26 @@ int DeriveKeys(WOLFSSL* ssl)
ret = StoreKeys(ssl, keyData, PROVISION_CLIENT_SERVER);
}

#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("DeriveKeys shaOutput", shaOutput, WC_SHA_DIGEST_SIZE);
wc_MemZero_Add("DeriveKeys md5Input", md5Input,
SECRET_LEN + WC_SHA_DIGEST_SIZE);
wc_MemZero_Add("DeriveKeys shaInput", shaInput,
KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN);
wc_MemZero_Add("DeriveKeys keyData", keyData,
KEY_PREFIX * WC_MD5_DIGEST_SIZE);
#endif
ForceZero(shaOutput, WC_SHA_DIGEST_SIZE);
ForceZero(md5Input, SECRET_LEN + WC_SHA_DIGEST_SIZE);
ForceZero(shaInput, KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN);
ForceZero(keyData, KEY_PREFIX * WC_MD5_DIGEST_SIZE);
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(shaOutput, WC_SHA_DIGEST_SIZE);
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wc_MemZero_Check(md5Input, SECRET_LEN + WC_SHA_DIGEST_SIZE);
wc_MemZero_Check(shaInput, KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN);
wc_MemZero_Check(keyData, KEY_PREFIX * WC_MD5_DIGEST_SIZE);
#endif
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WC_FREE_VAR_EX(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
Expand All @@ -3959,26 +3986,24 @@ int DeriveKeys(WOLFSSL* ssl)
}


static int CleanPreMaster(WOLFSSL* ssl)
static void CleanPreMaster(WOLFSSL* ssl)
{
int i, ret, sz = (int)(ssl->arrays->preMasterSz);
int sz = (int)(ssl->arrays->preMasterSz);

for (i = 0; i < sz; i++)
ssl->arrays->preMasterSecret[i] = 0;
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("CleanPreMaster preMasterSecret",
ssl->arrays->preMasterSecret, sz);
#endif

ret = wc_RNG_GenerateBlock(ssl->rng, ssl->arrays->preMasterSecret,
(word32)(sz));
if (ret != 0)
return ret;
ForceZero(ssl->arrays->preMasterSecret, sz);

for (i = 0; i < sz; i++)
ssl->arrays->preMasterSecret[i] = 0;
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(ssl->arrays->preMasterSecret, sz);
#endif

XFREE(ssl->arrays->preMasterSecret, ssl->heap, DYNAMIC_TYPE_SECRET);
ssl->arrays->preMasterSecret = NULL;
ssl->arrays->preMasterSz = 0;

return 0;
}


Expand Down Expand Up @@ -4038,6 +4063,13 @@ static int MakeSslMasterSecret(WOLFSSL* ssl)
return MEMORY_E;
}
#endif
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("MakeSslMasterSecret md5Input", md5Input,
ENCRYPT_LEN + WC_SHA_DIGEST_SIZE);
wc_MemZero_Add("MakeSslMasterSecret shaInput", shaInput,
PREFIX + ENCRYPT_LEN + 2 * RAN_LEN);
#endif

XMEMSET(shaOutput, 0, WC_SHA_DIGEST_SIZE);

ret = wc_InitMd5(md5);
Expand Down Expand Up @@ -4096,16 +4128,20 @@ static int MakeSslMasterSecret(WOLFSSL* ssl)
ret = DeriveKeys(ssl);
}

ForceZero(md5Input, ENCRYPT_LEN + WC_SHA_DIGEST_SIZE);
ForceZero(shaInput, PREFIX + ENCRYPT_LEN + 2 * RAN_LEN);
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(md5Input, ENCRYPT_LEN + WC_SHA_DIGEST_SIZE);
wc_MemZero_Check(shaInput, PREFIX + ENCRYPT_LEN + 2 * RAN_LEN);
#endif

WC_FREE_VAR_EX(shaOutput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(md5Input, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(shaInput, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(md5, NULL, DYNAMIC_TYPE_TMP_BUFFER);
WC_FREE_VAR_EX(sha, NULL, DYNAMIC_TYPE_TMP_BUFFER);

if (ret == 0)
ret = CleanPreMaster(ssl);
else
CleanPreMaster(ssl);
CleanPreMaster(ssl);

return ret;
}
Expand Down
8 changes: 8 additions & 0 deletions src/tls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -488,6 +488,14 @@ int DeriveTlsKeys(WOLFSSL* ssl)
if (ret == 0)
ret = StoreKeys(ssl, key_dig, PROVISION_CLIENT_SERVER);

#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("DeriveTlsKeys key_dig", key_dig, MAX_PRF_DIG);
#endif
ForceZero(key_dig, MAX_PRF_DIG);
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(key_dig, MAX_PRF_DIG);
#endif
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WC_FREE_VAR_EX(key_dig, ssl->heap, DYNAMIC_TYPE_DIGEST);

return ret;
Expand Down
46 changes: 30 additions & 16 deletions src/tls13.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1207,16 +1207,22 @@ int DeriveHandshakeSecret(WOLFSSL* ssl)
ret = DeriveKeyMsg(ssl, key, -1, ssl->arrays->secret,
derivedLabel, DERIVED_LABEL_SZ,
NULL, 0, ssl->specs.mac_algorithm);
if (ret != 0)
return ret;

PRIVATE_KEY_UNLOCK();
ret = Tls13_HKDF_Extract(ssl, ssl->arrays->preMasterSecret,
key, ssl->specs.hash_size,
ssl->arrays->preMasterSecret, (int)ssl->arrays->preMasterSz,
mac2hash(ssl->specs.mac_algorithm));
PRIVATE_KEY_LOCK();
if (ret == 0) {
PRIVATE_KEY_UNLOCK();
ret = Tls13_HKDF_Extract(ssl, ssl->arrays->preMasterSecret,
key, ssl->specs.hash_size,
ssl->arrays->preMasterSecret, (int)ssl->arrays->preMasterSz,
mac2hash(ssl->specs.mac_algorithm));
PRIVATE_KEY_LOCK();
}

#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("DeriveHandshakeSecret key", key, WC_MAX_DIGEST_SIZE);
#endif
ForceZero(key, sizeof(key));
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(key, sizeof(key));
#endif
return ret;
}

Expand Down Expand Up @@ -1244,14 +1250,22 @@ int DeriveMasterSecret(WOLFSSL* ssl)
ret = DeriveKeyMsg(ssl, key, -1, ssl->arrays->preMasterSecret,
derivedLabel, DERIVED_LABEL_SZ,
NULL, 0, ssl->specs.mac_algorithm);
if (ret != 0)
return ret;
if (ret == 0) {
PRIVATE_KEY_UNLOCK();
ret = Tls13_HKDF_Extract(ssl, ssl->arrays->masterSecret,
key, ssl->specs.hash_size,
ssl->arrays->masterSecret, 0,
mac2hash(ssl->specs.mac_algorithm));
PRIVATE_KEY_LOCK();
}

PRIVATE_KEY_UNLOCK();
ret = Tls13_HKDF_Extract(ssl, ssl->arrays->masterSecret,
key, ssl->specs.hash_size,
ssl->arrays->masterSecret, 0, mac2hash(ssl->specs.mac_algorithm));
PRIVATE_KEY_LOCK();
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Add("DeriveMasterSecret key", key, WC_MAX_DIGEST_SIZE);
#endif
ForceZero(key, sizeof(key));
#ifdef WOLFSSL_CHECK_MEM_ZERO
wc_MemZero_Check(key, sizeof(key));
#endif
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#ifdef HAVE_KEYING_MATERIAL
if (ret != 0)
Expand Down