Merge pull request #10247 from julek-wolfssl/fenrir/20260417

Fenrir fixes

Author: JacobBarthelmeh

src/pk.c

@@ -480,6 +480,7 @@ static int der_to_enc_pem_alloc(unsigned char* der, int derSz,
     byte* tmp = NULL;
     byte* cipherInfo = NULL;
     int pemSz = 0;
+    int derAllocSz = derSz;
     int hashType = WC_HASH_TYPE_NONE;
 #if !defined(NO_MD5)
     hashType = WC_MD5;
@@ -515,6 +516,7 @@ static int der_to_enc_pem_alloc(unsigned char* der, int derSz,
         }
         else {
             der = tmpBuf;
+            derAllocSz = derSz + blockSz;
 
             /* Encrypt DER inline. */
             ret = EncryptDerKey(der, &derSz, cipher, passwd, passwdSz,
@@ -562,7 +564,10 @@ static int der_to_enc_pem_alloc(unsigned char* der, int derSz,
 
     XFREE(tmp, NULL, DYNAMIC_TYPE_KEY);
     XFREE(cipherInfo, NULL, DYNAMIC_TYPE_STRING);
-    XFREE(der, heap, DYNAMIC_TYPE_TMP_BUFFER);
+    if (der != NULL) {
+        ForceZero(der, (word32)derAllocSz);
+        XFREE(der, heap, DYNAMIC_TYPE_TMP_BUFFER);
+    }
 
     return ret;
 }
@@ -2104,6 +2109,7 @@ int wolfSSL_PEM_write_mem_DSAPrivateKey(WOLFSSL_DSA* dsa,
     derSz = wc_DsaKeyToDer((DsaKey*)dsa->internal, derBuf, (word32)der_max_len);
     if (derSz < 0) {
         WOLFSSL_MSG("wc_DsaKeyToDer failed");
+        ForceZero(derBuf, (word32)der_max_len);
         XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
         return 0;
     }
@@ -2116,6 +2122,7 @@ int wolfSSL_PEM_write_mem_DSAPrivateKey(WOLFSSL_DSA* dsa,
             &cipherInfo, der_max_len, WC_MD5);
         if (ret != 1) {
             WOLFSSL_MSG("EncryptDerKey failed");
+            ForceZero(derBuf, (word32)der_max_len);
             XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
             return ret;
         }
@@ -2131,6 +2138,7 @@ int wolfSSL_PEM_write_mem_DSAPrivateKey(WOLFSSL_DSA* dsa,
     tmp = (byte*)XMALLOC((size_t)*pLen, NULL, DYNAMIC_TYPE_PEM);
     if (tmp == NULL) {
         WOLFSSL_MSG("malloc failed");
+        ForceZero(derBuf, (word32)der_max_len);
         XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
         XFREE(cipherInfo, NULL, DYNAMIC_TYPE_STRING);
         return 0;
@@ -2141,11 +2149,13 @@ int wolfSSL_PEM_write_mem_DSAPrivateKey(WOLFSSL_DSA* dsa,
         type);
     if (*pLen <= 0) {
         WOLFSSL_MSG("wc_DerToPemEx failed");
+        ForceZero(derBuf, (word32)der_max_len);
         XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
         XFREE(tmp, NULL, DYNAMIC_TYPE_PEM);
         XFREE(cipherInfo, NULL, DYNAMIC_TYPE_STRING);
         return 0;
     }
+    ForceZero(derBuf, (word32)der_max_len);
     XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
     XFREE(cipherInfo, NULL, DYNAMIC_TYPE_STRING);
 
@@ -7107,6 +7117,7 @@ static int pem_write_mem_pkcs8privatekey(byte** pem, int* pemSz,
     char password[NAME_SZ];
     byte* key = NULL;
     word32 keySz = 0;
+    word32 allocSz = 0;
     int type = PKCS8_PRIVATEKEY_TYPE;
 
     /* Validate parameters. */
@@ -7139,9 +7150,11 @@ static int pem_write_mem_pkcs8privatekey(byte** pem, int* pemSz,
             *pemSz += 54;
         }
 
+        allocSz = (word32)*pemSz;
         /* Allocate enough memory to hold PEM encoded encrypted key. */
-        *pem = (byte*)XMALLOC((size_t)*pemSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        *pem = (byte*)XMALLOC((size_t)allocSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
         if (*pem == NULL) {
+            allocSz = 0;
             res = 0;
         }
         else {
@@ -7198,6 +7211,20 @@ static int pem_write_mem_pkcs8privatekey(byte** pem, int* pemSz,
         }
     }
 
+    /* Zero any remnants of the DER staging area that persist after PEM
+     * conversion so plaintext private key material is not left in freed heap
+     * memory. On success, only the bytes past the actual PEM output need
+     * clearing; on failure, the whole buffer is zeroed since its state is
+     * indeterminate. */
+    if (*pem != NULL) {
+        if (res == 1 && (word32)*pemSz < allocSz) {
+            ForceZero(*pem + *pemSz, allocSz - (word32)*pemSz);
+        }
+        else if (res != 1) {
+            ForceZero(*pem, allocSz);
+        }
+    }
+
     /* Return appropriate return code. */
     return (res == 0) ? 0 : ret;
 

src/pk_ec.c

@@ -3524,6 +3524,9 @@ int wolfSSL_i2d_ECPrivateKey(const WOLFSSL_EC_KEY *key, unsigned char **out)
 
         /* Dispose of any allocated buffer on error. */
         if (err && (*out == buf)) {
+            if (buf != NULL) {
+                ForceZero(buf, len);
+            }
             XFREE(buf, NULL, DYNAMIC_TYPE_TMP_BUFFER);
             *out = NULL;
         }
@@ -4095,6 +4098,7 @@ int wolfSSL_PEM_write_mem_ECPrivateKey(WOLFSSL_EC_KEY* ec,
         derSz = wc_EccKeyToDer((ecc_key*)ec->internal, derBuf, der_max_len);
         if (derSz < 0) {
             WOLFSSL_MSG("wc_EccKeyToDer failed");
+            ForceZero(derBuf, der_max_len);
             XFREE(derBuf, NULL, DYNAMIC_TYPE_DER);
             ret = 0;
         }

src/pk_rsa.c

@@ -719,6 +719,9 @@ WOLFSSL_RSA* wolfSSL_d2i_RSAPrivateKey_bio(WOLFSSL_BIO *bio, WOLFSSL_RSA **out)
         key = NULL;
     }
     /* Dispose of allocated data. */
+    if (der != NULL) {
+        ForceZero(der, (word32)derLen);
+    }
     XFREE(der, bio ? bio->heap : NULL, DYNAMIC_TYPE_TMP_BUFFER);
     return key;
 }
@@ -779,6 +782,7 @@ static int wolfSSL_RSA_To_Der_ex(WOLFSSL_RSA* rsa, byte** outBuf, int publicKey,
 {
     int ret = 1;
     int derSz = 0;
+    word32 derAllocSz = 0;
     byte* derBuf = NULL;
 
     WOLFSSL_ENTER("wolfSSL_RSA_To_Der");
@@ -830,6 +834,9 @@ static int wolfSSL_RSA_To_Der_ex(WOLFSSL_RSA* rsa, byte** outBuf, int publicKey,
                 WOLFSSL_ERROR_MSG("Memory allocation failed");
                 ret = MEMORY_ERROR;
             }
+            else {
+                derAllocSz = (word32)derSz;
+            }
         }
     }
     if ((ret == 1) && (outBuf != NULL)) {
@@ -863,6 +870,9 @@ static int wolfSSL_RSA_To_Der_ex(WOLFSSL_RSA* rsa, byte** outBuf, int publicKey,
 
     if ((outBuf != NULL) && (*outBuf != derBuf)) {
         /* Not returning buffer, needs to be disposed of. */
+        if ((derBuf != NULL) && (publicKey == 0) && (derAllocSz > 0)) {
+            ForceZero(derBuf, derAllocSz);
+        }
         XFREE(derBuf, heap, DYNAMIC_TYPE_TMP_BUFFER);
     }
     WOLFSSL_LEAVE("wolfSSL_RSA_To_Der", ret);

src/sniffer.c

@@ -7242,12 +7242,16 @@ int ssl_SetWatchKey_file(void* vSniffer, const char* keyFile, int keyType,
     ret = LoadKeyFile(&keyBuf, &keyBufSz, keyFile, 0, keyType, password);
     if (ret < 0) {
         SetError(KEY_FILE_STR, error, NULL, 0);
+        if (keyBuf != NULL) {
+            ForceZero(keyBuf, keyBufSz);
+        }
         XFREE(keyBuf, NULL, DYNAMIC_TYPE_X509);
         return WOLFSSL_FATAL_ERROR;
     }
 
     ret = ssl_SetWatchKey_buffer(vSniffer, keyBuf, keyBufSz, FILETYPE_DER,
             error);
+    ForceZero(keyBuf, keyBufSz);
     XFREE(keyBuf, NULL, DYNAMIC_TYPE_X509);
 
     return ret;

src/ssl.c

@@ -18692,6 +18692,7 @@ static int SetStaticEphemeralKey(WOLFSSL_CTX* ctx,
 #ifndef NO_FILESYSTEM
     /* done with keyFile buffer */
     if (keyFile && keyBuf) {
+        ForceZero(keyBuf, keySz);
         XFREE(keyBuf, heap, DYNAMIC_TYPE_TMP_BUFFER);
     }
 #endif

src/ssl_load.c

@@ -5365,6 +5365,9 @@ int wolfSSL_CTX_use_RSAPrivateKey(WOLFSSL_CTX* ctx, WOLFSSL_RSA* rsa)
     }
 
     /* Dispos of dynamically allocated data. */
+    if (der != NULL) {
+        ForceZero(der, (word32)derSize);
+    }
     XFREE(der, NULL, DYNAMIC_TYPE_TMP_BUFFER);
     return ret;
 }