crypto: Clear temporary heap allocations before freeing

This reduces the time private keys may remain in heap memory after use.

Signed-off-by: Jouni Malinen <j@w1.fi>

hostapd/Makefile

@@ -962,6 +962,7 @@ hostapd_cli: $(OBJS_c)
 	@$(E) "  LD " $@
 
 NOBJS = nt_password_hash.o ../src/crypto/ms_funcs.o $(SHA1OBJS) ../src/crypto/md5.o
+NOBJS += ../src/utils/common.o
 ifdef NEED_RC4
 ifdef CONFIG_INTERNAL_RC4
 NOBJS += ../src/crypto/rc4.o

src/crypto/aes-eax.c

@@ -71,7 +71,7 @@ int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
 
 	ret = 0;
 fail:
-	os_free(buf);
+	bin_clear_free(buf, buf_len);
 
 	return ret;
 }

src/crypto/aes-siv.c

@@ -95,7 +95,7 @@ static int aes_s2v(const u8 *key, size_t num_elem, const u8 *addr[],
 		os_memcpy(buf, addr[i], len[i]);
 		xorend(buf, len[i], tmp, AES_BLOCK_SIZE);
 		ret = omac1_aes_128(key, buf, len[i], mac);
-		os_free(buf);
+		bin_clear_free(buf, len[i]);
 		return ret;
 	}
 

src/crypto/crypto_openssl.c

@@ -258,7 +258,7 @@ void aes_encrypt_deinit(void *ctx)
 			   "in AES encrypt", len);
 	}
 	EVP_CIPHER_CTX_cleanup(c);
-	os_free(c);
+	bin_clear_free(c, sizeof(*c));
 }
 
 
@@ -309,7 +309,7 @@ void aes_decrypt_deinit(void *ctx)
 			   "in AES decrypt", len);
 	}
 	EVP_CIPHER_CTX_cleanup(c);
-	os_free(ctx);
+	bin_clear_free(c, sizeof(*c));
 }
 
 
@@ -507,8 +507,8 @@ void * dh5_init(struct wpabuf **priv, struct wpabuf **publ)
 	return dh;
 
 err:
-	wpabuf_free(pubkey);
-	wpabuf_free(privkey);
+	wpabuf_clear_free(pubkey);
+	wpabuf_clear_free(privkey);
 	DH_free(dh);
 	return NULL;
 }
@@ -581,7 +581,7 @@ struct wpabuf * dh5_derive_shared(void *ctx, const struct wpabuf *peer_public,
 
 err:
 	BN_clear_free(pub_key);
-	wpabuf_free(res);
+	wpabuf_clear_free(res);
 	return NULL;
 }
 
@@ -638,7 +638,7 @@ struct crypto_hash * crypto_hash_init(enum crypto_hash_alg alg, const u8 *key,
 	HMAC_Init_ex(&ctx->ctx, key, key_len, md, NULL);
 #else /* openssl < 0.9.9 */
 	if (HMAC_Init_ex(&ctx->ctx, key, key_len, md, NULL) != 1) {
-		os_free(ctx);
+		bin_clear_free(ctx, sizeof(*ctx));
 		return NULL;
 	}
 #endif /* openssl < 0.9.9 */
@@ -664,7 +664,7 @@ int crypto_hash_finish(struct crypto_hash *ctx, u8 *mac, size_t *len)
 		return -2;
 
 	if (mac == NULL || len == NULL) {
-		os_free(ctx);
+		bin_clear_free(ctx, sizeof(*ctx));
 		return 0;
 	}
 
@@ -676,7 +676,7 @@ int crypto_hash_finish(struct crypto_hash *ctx, u8 *mac, size_t *len)
 	res = HMAC_Final(&ctx->ctx, mac, &mdlen);
 #endif /* openssl < 0.9.9 */
 	HMAC_CTX_cleanup(&ctx->ctx);
-	os_free(ctx);
+	bin_clear_free(ctx, sizeof(*ctx));
 
 	if (res == 1) {
 		*len = mdlen;