Add and use k5memdup, k5memdup0 helpers

Add k5-int.h static functions to duplicate byte ranges, optionally
with a trailing zero byte, and set an error code like k5alloc does.
Use them where they would shorten existing code.

3 files changed, 6 insertions, 9 deletions

diff --git a/src/lib/crypto/krb/checksum_confounder.c b/src/lib/crypto/krb/checksum_confounder.c
index 116b3c7ff0..afc473bfe3 100644
--- a/src/lib/crypto/krb/checksum_confounder.c
+++ b/src/lib/crypto/krb/checksum_confounder.c
@@ -41,10 +41,10 @@ mk_xorkey(krb5_key origkey, krb5_key *xorkey)
     krb5_keyblock xorkeyblock;
     size_t i = 0;
 
-    xorbytes = malloc(origkey->keyblock.length);
+    xorbytes = k5memdup(origkey->keyblock.contents, origkey->keyblock.length,
+                        &retval);
     if (xorbytes == NULL)
-        return ENOMEM;
-    memcpy(xorbytes, origkey->keyblock.contents, origkey->keyblock.length);
+        return retval;
     for (i = 0; i < origkey->keyblock.length; i++)
         xorbytes[i] ^= 0xf0;
 
@@ -118,7 +118,7 @@ krb5_error_code krb5int_confounder_verify(const struct krb5_cksumtypes *ctp,
     krb5_crypto_iov *hash_iov = NULL, iov;
     size_t blocksize = ctp->enc->block_size, hashsize = ctp->hash->hashsize;
 
-    plaintext = k5alloc(input->length, &ret);
+    plaintext = k5memdup(input->data, input->length, &ret);
     if (plaintext == NULL)
         return ret;
 
@@ -129,7 +129,6 @@ krb5_error_code krb5int_confounder_verify(const struct krb5_cksumtypes *ctp,
     /* Decrypt the input checksum. */
     iov.flags = KRB5_CRYPTO_TYPE_DATA;
     iov.data = make_data(plaintext, input->length);
-    memcpy(plaintext, input->data, input->length);
     ret = ctp->enc->decrypt(xorkey, NULL, &iov, 1);
     if (ret != 0)
         goto cleanup;
diff --git a/src/lib/crypto/krb/derive.c b/src/lib/crypto/krb/derive.c
index 1509f42250..f15fec1a29 100644
--- a/src/lib/crypto/krb/derive.c
+++ b/src/lib/crypto/krb/derive.c
@@ -52,7 +52,7 @@ add_cached_dkey(krb5_key key, const krb5_data *constant,
     dkent = malloc(sizeof(*dkent));
     if (dkent == NULL)
         goto cleanup;
-    data = malloc(constant->length);
+    data = k5memdup(constant->data, constant->length, &ret);
     if (data == NULL)
         goto cleanup;
     ret = krb5_k_create_key(NULL, dkeyblock, &dkey);
@@ -60,7 +60,6 @@ add_cached_dkey(krb5_key key, const krb5_data *constant,
         goto cleanup;
 
     /* Add the new entry to the list. */
-    memcpy(data, constant->data, constant->length);
     dkent->dkey = dkey;
     dkent->constant.data = data;
     dkent->constant.length = constant->length;
diff --git a/src/lib/crypto/krb/enc_old.c b/src/lib/crypto/krb/enc_old.c
index e7160b1692..b44a3994f0 100644
--- a/src/lib/crypto/krb/enc_old.c
+++ b/src/lib/crypto/krb/enc_old.c
@@ -166,10 +166,9 @@ krb5int_old_decrypt(const struct krb5_keytypes *ktp, krb5_key key,
 
     /* Save the checksum, then zero it out in the plaintext. */
     checksum = make_data(header->data.data + enc->block_size, hash->hashsize);
-    saved_checksum = k5alloc(hash->hashsize, &ret);
+    saved_checksum = k5memdup(checksum.data, checksum.length, &ret);
     if (saved_checksum == NULL)
         goto cleanup;
-    memcpy(saved_checksum, checksum.data, checksum.length);
     memset(checksum.data, 0, checksum.length);
 
     /*