Revamp cmac_nif()

* Add error checking on all OpenSSL and Erlang calls.

1 files changed, 37 insertions, 23 deletions

diff --git a/lib/crypto/c_src/cmac.c b/lib/crypto/c_src/cmac.c
index 526de11a01..303b7af6eb 100644
--- a/lib/crypto/c_src/cmac.c
+++ b/lib/crypto/c_src/cmac.c
@@ -26,40 +26,54 @@ ERL_NIF_TERM cmac_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
 #if defined(HAVE_CMAC)
     struct cipher_type_t *cipherp = NULL;
     const EVP_CIPHER     *cipher;
-    CMAC_CTX             *ctx;
+    CMAC_CTX             *ctx = NULL;
     ErlNifBinary         key;
     ErlNifBinary         data;
     ERL_NIF_TERM         ret;
     size_t               ret_size;
+    unsigned char       *outp;
+    int                  cipher_len;
 
-    if (!enif_inspect_iolist_as_binary(env, argv[1], &key)
-        || !(cipherp = get_cipher_type(argv[0], key.size))
-        || !enif_inspect_iolist_as_binary(env, argv[2], &data)) {
-        return enif_make_badarg(env);
-    }
-    cipher = cipherp->cipher.p;
-    if (!cipher) {
+    if (argc != 3)
+        goto bad_arg;
+    if (!enif_inspect_iolist_as_binary(env, argv[1], &key))
+        goto bad_arg;
+    if ((cipherp = get_cipher_type(argv[0], key.size)) == NULL)
+        goto bad_arg;
+    if (!enif_inspect_iolist_as_binary(env, argv[2], &data))
+        goto bad_arg;
+
+    if ((cipher = cipherp->cipher.p) == NULL)
         return enif_raise_exception(env, atom_notsup);
-    }
 
-    ctx = CMAC_CTX_new();
-    if (!CMAC_Init(ctx, key.data, key.size, cipher, NULL)) {
-        CMAC_CTX_free(ctx);
-        return atom_notsup;
-    }
+    if ((ctx = CMAC_CTX_new()) == NULL)
+        goto err;
+    if (!CMAC_Init(ctx, key.data, key.size, cipher, NULL))
+        goto err;
+    if (!CMAC_Update(ctx, data.data, data.size))
+        goto err;
+    if ((cipher_len = EVP_CIPHER_block_size(cipher)) < 0)
+        goto err;
+    if ((outp = enif_make_new_binary(env, (size_t)cipher_len, &ret)) == NULL)
+        goto err;
+    if (!CMAC_Final(ctx, outp, &ret_size))
+        goto err;
 
-    if (!CMAC_Update(ctx, data.data, data.size) ||
-        !CMAC_Final(ctx,
-                    enif_make_new_binary(env, EVP_CIPHER_block_size(cipher), &ret),
-                    &ret_size)) {
-        CMAC_CTX_free(ctx);
-        return atom_notsup;
-    }
     ASSERT(ret_size == (unsigned)EVP_CIPHER_block_size(cipher));
-
-    CMAC_CTX_free(ctx);
     CONSUME_REDS(env, data);
+    goto done;
+
+ bad_arg:
+    return enif_make_badarg(env);
+
+ err:
+    ret = atom_notsup;
+
+ done:
+    if (ctx)
+        CMAC_CTX_free(ctx);
     return ret;
+
 #else
     /* The CMAC functionality was introduced in OpenSSL 1.0.1
      * Although OTP requires at least version 0.9.8, the versions 0.9.8 and 1.0.0 are