[Qemu-devel] [PATCH for 4.2 3/3] crypto: use auto cleanup for many stack variables

[Daniel P . Berrangé]

Simplify cleanup paths by using glib's auto cleanup macros for stack
variables, allowing several goto jumps / labels to be eliminated.

Signed-off-by: Daniel P. Berrangé <address@hidden>
---
 crypto/afsplit.c      | 28 +++++-----------
 crypto/block-luks.c   | 74 +++++++++++++------------------------------
 crypto/block.c        | 15 +++------
 crypto/pbkdf.c        |  5 +--
 crypto/secret.c       |  9 +++---
 crypto/tlscredsanon.c | 16 ++++------
 crypto/tlscredspsk.c  |  5 ++-
 crypto/tlscredsx509.c | 16 +++-------
 8 files changed, 53 insertions(+), 115 deletions(-)

diff --git a/crypto/afsplit.c b/crypto/afsplit.c
index 328d68c96b..b1a5a20899 100644
--- a/crypto/afsplit.c
+++ b/crypto/afsplit.c
@@ -58,7 +58,7 @@ static int qcrypto_afsplit_hash(QCryptoHashAlgorithm hash,
     }
 
     for (i = 0; i < hashcount; i++) {
-        uint8_t *out = NULL;
+        g_autofree uint8_t *out = NULL;
         size_t outlen = 0;
         uint32_t iv = cpu_to_be32(i);
         struct iovec in[] = {
@@ -79,7 +79,6 @@ static int qcrypto_afsplit_hash(QCryptoHashAlgorithm hash,
         assert(outlen == digestlen);
         memcpy(block + (i * digestlen), out,
                (i == (hashcount - 1)) ? finallen : digestlen);
-        g_free(out);
     }
 
     return 0;
@@ -93,13 +92,12 @@ int qcrypto_afsplit_encode(QCryptoHashAlgorithm hash,
                            uint8_t *out,
                            Error **errp)
 {
-    uint8_t *block = g_new0(uint8_t, blocklen);
+    g_autofree uint8_t *block = g_new0(uint8_t, blocklen);
     size_t i;
-    int ret = -1;
 
     for (i = 0; i < (stripes - 1); i++) {
         if (qcrypto_random_bytes(out + (i * blocklen), blocklen, errp) < 0) {
-            goto cleanup;
+            return -1;
         }
 
         qcrypto_afsplit_xor(blocklen,
@@ -108,18 +106,14 @@ int qcrypto_afsplit_encode(QCryptoHashAlgorithm hash,
                             block);
         if (qcrypto_afsplit_hash(hash, blocklen, block,
                                  errp) < 0) {
-            goto cleanup;
+            return -1;
         }
     }
     qcrypto_afsplit_xor(blocklen,
                         in,
                         block,
                         out + (i * blocklen));
-    ret = 0;
-
- cleanup:
-    g_free(block);
-    return ret;
+    return 0;
 }
 
 
@@ -130,9 +124,8 @@ int qcrypto_afsplit_decode(QCryptoHashAlgorithm hash,
                            uint8_t *out,
                            Error **errp)
 {
-    uint8_t *block = g_new0(uint8_t, blocklen);
+    g_autofree uint8_t *block = g_new0(uint8_t, blocklen);
     size_t i;
-    int ret = -1;
 
     for (i = 0; i < (stripes - 1); i++) {
         qcrypto_afsplit_xor(blocklen,
@@ -141,7 +134,7 @@ int qcrypto_afsplit_decode(QCryptoHashAlgorithm hash,
                             block);
         if (qcrypto_afsplit_hash(hash, blocklen, block,
                                  errp) < 0) {
-            goto cleanup;
+            return -1;
         }
     }
 
@@ -149,10 +142,5 @@ int qcrypto_afsplit_decode(QCryptoHashAlgorithm hash,
                         in + (i * blocklen),
                         block,
                         out);
-
-    ret = 0;
-
- cleanup:
-    g_free(block);
-    return ret;
+    return 0;
 }
diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index 409ab50f20..c8e0a0caa4 100644
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -425,14 +425,13 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                             Error **errp)
 {
     QCryptoBlockLUKS *luks = block->opaque;
-    uint8_t *splitkey;
+    g_autofree uint8_t *splitkey = NULL;
     size_t splitkeylen;
-    uint8_t *possiblekey;
-    int ret = -1;
+    g_autofree uint8_t *possiblekey = NULL;
     ssize_t rv;
-    QCryptoCipher *cipher = NULL;
+    g_autoptr(QCryptoCipher) cipher = NULL;
     uint8_t keydigest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
-    QCryptoIVGen *ivgen = NULL;
+    g_autoptr(QCryptoIVGen) ivgen = NULL;
     size_t niv;
 
     if (slot->active != QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED) {
@@ -456,7 +455,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                        slot->iterations,
                        possiblekey, masterkeylen,
                        errp) < 0) {
-        goto cleanup;
+        return -1;
     }
 
     /*
@@ -472,7 +471,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                   opaque,
                   errp);
     if (rv < 0) {
-        goto cleanup;
+        return -1;
     }
 
 
@@ -482,7 +481,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                                 possiblekey, masterkeylen,
                                 errp);
     if (!cipher) {
-        goto cleanup;
+        return -1;
     }
 
     niv = qcrypto_cipher_get_iv_len(cipheralg,
@@ -493,7 +492,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                               possiblekey, masterkeylen,
                               errp);
     if (!ivgen) {
-        goto cleanup;
+        return -1;
     }
 
 
@@ -512,7 +511,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                                             splitkey,
                                             splitkeylen,
                                             errp) < 0) {
-        goto cleanup;
+        return -1;
     }
 
     /*
@@ -525,7 +524,7 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                                splitkey,
                                masterkey,
                                errp) < 0) {
-        goto cleanup;
+        return -1;
     }
 
 
@@ -544,26 +543,18 @@ qcrypto_block_luks_load_key(QCryptoBlock *block,
                        luks->header.master_key_iterations,
                        keydigest, G_N_ELEMENTS(keydigest),
                        errp) < 0) {
-        goto cleanup;
+        return -1;
     }
 
     if (memcmp(keydigest, luks->header.master_key_digest,
                QCRYPTO_BLOCK_LUKS_DIGEST_LEN) == 0) {
         /* Success, we got the right master key */
-        ret = 1;
-        goto cleanup;
+        return 1;
     }
 
     /* Fail, user's password was not valid for this key slot,
      * tell caller to try another slot */
-    ret = 0;
-
- cleanup:
-    qcrypto_ivgen_free(ivgen);
-    qcrypto_cipher_free(cipher);
-    g_free(splitkey);
-    g_free(possiblekey);
-    return ret;
+    return 0;
 }
 
 
@@ -644,7 +635,7 @@ qcrypto_block_luks_open(QCryptoBlock *block,
     int ret = 0;
     size_t i;
     ssize_t rv;
-    uint8_t *masterkey = NULL;
+    g_autofree uint8_t *masterkey = NULL;
     size_t masterkeylen;
     char *ivgen_name, *ivhash_name;
     QCryptoCipherMode ciphermode;
@@ -653,7 +644,7 @@ qcrypto_block_luks_open(QCryptoBlock *block,
     QCryptoCipherAlgorithm ivcipheralg;
     QCryptoHashAlgorithm hash;
     QCryptoHashAlgorithm ivhash;
-    char *password = NULL;
+    g_autofree char *password = NULL;
 
     if (!(flags & QCRYPTO_BLOCK_OPEN_NO_IO)) {
         if (!options->u.luks.key_secret) {
@@ -856,17 +847,12 @@ qcrypto_block_luks_open(QCryptoBlock *block,
     luks->ivgen_hash_alg = ivhash;
     luks->hash_alg = hash;
 
-    g_free(masterkey);
-    g_free(password);
-
     return 0;
 
  fail:
-    g_free(masterkey);
     qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
     g_free(luks);
-    g_free(password);
     return ret;
 }
 
@@ -891,20 +877,20 @@ qcrypto_block_luks_create(QCryptoBlock *block,
     QCryptoBlockLUKS *luks;
     QCryptoBlockCreateOptionsLUKS luks_opts;
     Error *local_err = NULL;
-    uint8_t *masterkey = NULL;
-    uint8_t *slotkey = NULL;
-    uint8_t *splitkey = NULL;
+    g_autofree uint8_t *masterkey = NULL;
+    g_autofree uint8_t *slotkey = NULL;
+    g_autofree uint8_t *splitkey = NULL;
     size_t splitkeylen = 0;
     size_t i;
-    QCryptoCipher *cipher = NULL;
-    QCryptoIVGen *ivgen = NULL;
-    char *password;
+    g_autoptr(QCryptoCipher) cipher = NULL;
+    g_autoptr(QCryptoIVGen) ivgen = NULL;
+    g_autofree char *password;
     const char *cipher_alg;
     const char *cipher_mode;
     const char *ivgen_alg;
     const char *ivgen_hash_alg = NULL;
     const char *hash_alg;
-    char *cipher_mode_spec = NULL;
+    g_autofree char *cipher_mode_spec = NULL;
     QCryptoCipherAlgorithm ivcipheralg = 0;
     uint64_t iters;
 
@@ -1311,15 +1297,7 @@ qcrypto_block_luks_create(QCryptoBlock *block,
     luks->hash_alg = luks_opts.hash_alg;
 
     memset(masterkey, 0, luks->header.key_bytes);
-    g_free(masterkey);
     memset(slotkey, 0, luks->header.key_bytes);
-    g_free(slotkey);
-    g_free(splitkey);
-    g_free(password);
-    g_free(cipher_mode_spec);
-
-    qcrypto_ivgen_free(ivgen);
-    qcrypto_cipher_free(cipher);
 
     return 0;
 
@@ -1327,17 +1305,9 @@ qcrypto_block_luks_create(QCryptoBlock *block,
     if (masterkey) {
         memset(masterkey, 0, luks->header.key_bytes);
     }
-    g_free(masterkey);
     if (slotkey) {
         memset(slotkey, 0, luks->header.key_bytes);
     }
-    g_free(slotkey);
-    g_free(splitkey);
-    g_free(password);
-    g_free(cipher_mode_spec);
-
-    qcrypto_ivgen_free(ivgen);
-    qcrypto_cipher_free(cipher);
 
     qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
diff --git a/crypto/block.c b/crypto/block.c
index ee96759f7d..325752871c 100644
--- a/crypto/block.c
+++ b/crypto/block.c
@@ -299,15 +299,13 @@ static int do_qcrypto_block_cipher_encdec(QCryptoCipher 
*cipher,
                                           QCryptoCipherEncDecFunc func,
                                           Error **errp)
 {
-    uint8_t *iv;
+    g_autofree uint8_t *iv = niv ? g_new0(uint8_t, niv) : NULL;
     int ret = -1;
     uint64_t startsector = offset / sectorsize;
 
     assert(QEMU_IS_ALIGNED(offset, sectorsize));
     assert(QEMU_IS_ALIGNED(len, sectorsize));
 
-    iv = niv ? g_new0(uint8_t, niv) : NULL;
-
     while (len > 0) {
         size_t nbytes;
         if (niv) {
@@ -320,19 +318,19 @@ static int do_qcrypto_block_cipher_encdec(QCryptoCipher 
*cipher,
             }
 
             if (ret < 0) {
-                goto cleanup;
+                return -1;
             }
 
             if (qcrypto_cipher_setiv(cipher,
                                      iv, niv,
                                      errp) < 0) {
-                goto cleanup;
+                return -1;
             }
         }
 
         nbytes = len > sectorsize ? sectorsize : len;
         if (func(cipher, buf, buf, nbytes, errp) < 0) {
-            goto cleanup;
+            return -1;
         }
 
         startsector++;
@@ -340,10 +338,7 @@ static int do_qcrypto_block_cipher_encdec(QCryptoCipher 
*cipher,
         len -= nbytes;
     }
 
-    ret = 0;
- cleanup:
-    g_free(iv);
-    return ret;
+    return 0;
 }
 
 
diff --git a/crypto/pbkdf.c b/crypto/pbkdf.c
index b7c7c4a59b..3775ddc6c5 100644
--- a/crypto/pbkdf.c
+++ b/crypto/pbkdf.c
@@ -69,12 +69,10 @@ uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm 
hash,
                                     Error **errp)
 {
     uint64_t ret = -1;
-    uint8_t *out;
+    g_autofree uint8_t *out = g_new(uint8_t, nout);
     uint64_t iterations = (1 << 15);
     unsigned long long delta_ms, start_ms, end_ms;
 
-    out = g_new(uint8_t, nout);
-
     while (1) {
         if (qcrypto_pbkdf2_get_thread_cpu(&start_ms, errp) < 0) {
             goto cleanup;
@@ -108,6 +106,5 @@ uint64_t qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm 
hash,
 
  cleanup:
     memset(out, 0, nout);
-    g_free(out);
     return ret;
 }
diff --git a/crypto/secret.c b/crypto/secret.c
index a75d50ae0c..aeb506afab 100644
--- a/crypto/secret.c
+++ b/crypto/secret.c
@@ -72,9 +72,11 @@ static void qcrypto_secret_decrypt(QCryptoSecret *secret,
                                    size_t *outputlen,
                                    Error **errp)
 {
-    uint8_t *key = NULL, *ciphertext = NULL, *iv = NULL;
+    g_autofree uint8_t *key = NULL;
+    g_autofree uint8_t *ciphertext = NULL;
+    g_autofree uint8_t *iv = NULL;
     size_t keylen, ciphertextlen, ivlen;
-    QCryptoCipher *aes = NULL;
+    g_autoptr(QCryptoCipher) aes = NULL;
     uint8_t *plaintext = NULL;
 
     *output = NULL;
@@ -160,9 +162,6 @@ static void qcrypto_secret_decrypt(QCryptoSecret *secret,
     *outputlen = ciphertextlen;
 
  cleanup:
-    g_free(ciphertext);
-    g_free(iv);
-    g_free(key);
     qcrypto_cipher_free(aes);
 }
 
diff --git a/crypto/tlscredsanon.c b/crypto/tlscredsanon.c
index d2adc7c131..a235f60146 100644
--- a/crypto/tlscredsanon.c
+++ b/crypto/tlscredsanon.c
@@ -34,9 +34,8 @@ static int
 qcrypto_tls_creds_anon_load(QCryptoTLSCredsAnon *creds,
                             Error **errp)
 {
-    char *dhparams = NULL;
+    g_autofree char *dhparams = NULL;
     int ret;
-    int rv = -1;
 
     trace_qcrypto_tls_creds_anon_load(creds,
             creds->parent_obj.dir ? creds->parent_obj.dir : "<nodir>");
@@ -45,20 +44,20 @@ qcrypto_tls_creds_anon_load(QCryptoTLSCredsAnon *creds,
         if (qcrypto_tls_creds_get_path(&creds->parent_obj,
                                        QCRYPTO_TLS_CREDS_DH_PARAMS,
                                        false, &dhparams, errp) < 0) {
-            goto cleanup;
+            return -1;
         }
 
         ret = gnutls_anon_allocate_server_credentials(&creds->data.server);
         if (ret < 0) {
             error_setg(errp, "Cannot allocate credentials: %s",
                        gnutls_strerror(ret));
-            goto cleanup;
+            return -1;
         }
 
         if (qcrypto_tls_creds_get_dh_params_file(&creds->parent_obj, dhparams,
                                                  &creds->parent_obj.dh_params,
                                                  errp) < 0) {
-            goto cleanup;
+            return -1;
         }
 
         gnutls_anon_set_server_dh_params(creds->data.server,
@@ -68,14 +67,11 @@ qcrypto_tls_creds_anon_load(QCryptoTLSCredsAnon *creds,
         if (ret < 0) {
             error_setg(errp, "Cannot allocate credentials: %s",
                        gnutls_strerror(ret));
-            goto cleanup;
+            return -1;
         }
     }
 
-    rv = 0;
- cleanup:
-    g_free(dhparams);
-    return rv;
+    return 0;
 }
 
 
diff --git a/crypto/tlscredspsk.c b/crypto/tlscredspsk.c
index 4b6cf636ce..15d12e2448 100644
--- a/crypto/tlscredspsk.c
+++ b/crypto/tlscredspsk.c
@@ -69,7 +69,8 @@ static int
 qcrypto_tls_creds_psk_load(QCryptoTLSCredsPSK *creds,
                            Error **errp)
 {
-    char *pskfile = NULL, *dhparams = NULL;
+    g_autofree char *pskfile = NULL;
+    g_autofree char *dhparams = NULL;
     const char *username;
     int ret;
     int rv = -1;
@@ -139,8 +140,6 @@ qcrypto_tls_creds_psk_load(QCryptoTLSCredsPSK *creds,
     rv = 0;
  cleanup:
     g_free(key.data);
-    g_free(pskfile);
-    g_free(dhparams);
     return rv;
 }
 
diff --git a/crypto/tlscredsx509.c b/crypto/tlscredsx509.c
index 56dcef3673..01fc304e5d 100644
--- a/crypto/tlscredsx509.c
+++ b/crypto/tlscredsx509.c
@@ -378,7 +378,7 @@ qcrypto_tls_creds_load_cert(QCryptoTLSCredsX509 *creds,
 {
     gnutls_datum_t data;
     gnutls_x509_crt_t cert = NULL;
-    char *buf = NULL;
+    g_autofree char *buf = NULL;
     gsize buflen;
     GError *gerr;
     int ret = -1;
@@ -420,7 +420,6 @@ qcrypto_tls_creds_load_cert(QCryptoTLSCredsX509 *creds,
         gnutls_x509_crt_deinit(cert);
         cert = NULL;
     }
-    g_free(buf);
     return cert;
 }
 
@@ -434,9 +433,8 @@ qcrypto_tls_creds_load_ca_cert_list(QCryptoTLSCredsX509 
*creds,
                                     Error **errp)
 {
     gnutls_datum_t data;
-    char *buf = NULL;
+    g_autofree char *buf = NULL;
     gsize buflen;
-    int ret = -1;
     GError *gerr = NULL;
 
     *ncerts = 0;
@@ -446,7 +444,7 @@ qcrypto_tls_creds_load_ca_cert_list(QCryptoTLSCredsX509 
*creds,
         error_setg(errp, "Cannot load CA cert list %s: %s",
                    certFile, gerr->message);
         g_error_free(gerr);
-        goto cleanup;
+        return -1;
     }
 
     data.data = (unsigned char *)buf;
@@ -457,15 +455,11 @@ qcrypto_tls_creds_load_ca_cert_list(QCryptoTLSCredsX509 
*creds,
         error_setg(errp,
                    "Unable to import CA certificate list %s",
                    certFile);
-        goto cleanup;
+        return -1;
     }
     *ncerts = certMax;
 
-    ret = 0;
-
- cleanup:
-    g_free(buf);
-    return ret;
+    return 0;
 }
 
 
-- 
2.21.0