s4-auth: Make sure error_string is correctly initialized

This should avoid a possible double free.

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>

diff --git a/source4/auth/kerberos/srv_keytab.c b/source4/auth/kerberos/srv_keytab.c
index ed7b1a39183bfb827826d836cb6c7b8178246b63..6e02b8184ced4e801e4e9b33bd73fadf15b9dd81 100644 (file)
--- a/source4/auth/kerberos/srv_keytab.c
+++ b/source4/auth/kerberos/srv_keytab.c
@@ -70,6 +70,8 @@ static krb5_error_code keytab_add_keys(TALLOC_CTX *parent_ctx,
                                                      enctypes[i],
                                                      KRB5_KT_KEY(&entry));
                if (ret != 0) {
+                       *error_string = talloc_strdup(parent_ctx,
+                                                     "Failed to create key from string");
                        return ret;
                }
 
@@ -119,12 +121,13 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
                                     krb5_context context,
                                     krb5_keytab keytab,
                                     bool add_old,
-                                    const char **error_string)
+                                    const char **perror_string)
 {
        krb5_error_code ret;
        krb5_principal salt_princ = NULL;
        krb5_enctype *enctypes;
        TALLOC_CTX *mem_ctx;
+       const char *error_string = NULL;
 
        if (!new_secret) {
                /* There is no password here, so nothing to do */
@@ -133,7 +136,7 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 
        mem_ctx = talloc_new(parent_ctx);
        if (!mem_ctx) {
-               *error_string = talloc_strdup(parent_ctx,
+               *perror_string = talloc_strdup(parent_ctx,
                        "unable to allocate tmp_ctx for create_keytab");
                return ENOMEM;
        }
@@ -142,7 +145,7 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
         * fetch that */
        ret = krb5_parse_name(context, saltPrincipal, &salt_princ);
        if (ret) {
-               *error_string = smb_get_krb5_error_message(context,
+               *perror_string = smb_get_krb5_error_message(context,
                                                           ret,
                                                           parent_ctx);
                talloc_free(mem_ctx);
@@ -151,7 +154,7 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
 
        ret = ms_suptypes_to_ietf_enctypes(mem_ctx, supp_enctypes, &enctypes);
        if (ret) {
-               *error_string = talloc_asprintf(parent_ctx,
+               *perror_string = talloc_asprintf(parent_ctx,
                                        "create_keytab: generating list of "
                                        "encryption types failed (%s)\n",
                                        smb_get_krb5_error_message(context,
@@ -163,9 +166,9 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
                              num_principals,
                              principals,
                              salt_princ, kvno, new_secret,
-                             context, enctypes, keytab, error_string);
+                             context, enctypes, keytab, &error_string);
        if (ret) {
-               talloc_steal(parent_ctx, *error_string);
+               *perror_string = talloc_steal(parent_ctx, error_string);
                goto done;
        }
 
@@ -174,9 +177,9 @@ static krb5_error_code create_keytab(TALLOC_CTX *parent_ctx,
                                      num_principals,
                                      principals,
                                      salt_princ, kvno - 1, old_secret,
-                                     context, enctypes, keytab, error_string);
+                                     context, enctypes, keytab, &error_string);
                if (ret) {
-                       talloc_steal(parent_ctx, *error_string);
+                       *perror_string = talloc_steal(parent_ctx, error_string);
                }
        }
 
@@ -200,7 +203,7 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
                                uint32_t supp_enctypes,
                                bool delete_all_kvno,
                                krb5_keytab *_keytab,
-                               const char **error_string)
+                               const char **perror_string)
 {
        krb5_keytab keytab;
        krb5_error_code ret;
@@ -209,19 +212,21 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
        krb5_principal *principals = NULL;
        uint32_t num_principals = 0;
        char *upper_realm;
+       const char *error_string = NULL;
 
        if (keytab_name == NULL) {
                return ENOENT;
        }
 
        if (saltPrincipal == NULL) {
-               *error_string = "No saltPrincipal provided";
+               *perror_string = talloc_strdup(parent_ctx,
+                                             "No saltPrincipal provided");
                return EINVAL;
        }
 
        ret = krb5_kt_resolve(context, keytab_name, &keytab);
        if (ret) {
-               *error_string = smb_get_krb5_error_message(context,
+               *perror_string = smb_get_krb5_error_message(context,
                                                           ret, parent_ctx);
                return ret;
        }
@@ -230,12 +235,15 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
 
        tmp_ctx = talloc_new(parent_ctx);
        if (!tmp_ctx) {
+               *perror_string = talloc_strdup(parent_ctx,
+                                             "Failed to allocate memory context");
                return ENOMEM;
        }
 
        upper_realm = strupper_talloc(tmp_ctx, realm);
        if (upper_realm == NULL) {
-               *error_string = "Cannot allocate memory to upper case realm";
+               *perror_string = talloc_strdup(parent_ctx,
+                                             "Cannot allocate memory to upper case realm");
                talloc_free(tmp_ctx);
                return ENOMEM;
        }
@@ -248,11 +256,11 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
                                               SPNs,
                                               &num_principals,
                                               &principals,
-                                              error_string);
+                                              &error_string);
        if (ret != 0) {
-               *error_string = talloc_asprintf(parent_ctx,
+               *perror_string = talloc_asprintf(parent_ctx,
                        "Failed to load principals from ldb message: %s\n",
-                       *error_string);
+                       error_string);
                goto done;
        }
 
@@ -263,11 +271,11 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
                                                      principals,
                                                      kvno,
                                                      &found_previous,
-                                                     error_string);
+                                                     &error_string);
        if (ret != 0) {
-               *error_string = talloc_asprintf(parent_ctx,
+               *perror_string = talloc_asprintf(parent_ctx,
                        "Failed to remove old principals from keytab: %s\n",
-                       *error_string);
+                       error_string);
                goto done;
        }
 
@@ -284,9 +292,9 @@ krb5_error_code smb_krb5_update_keytab(TALLOC_CTX *parent_ctx,
                                    principals,
                                    context, keytab,
                                    found_previous ? false : true,
-                                   error_string);
+                                   &error_string);
                if (ret) {
-                       talloc_steal(parent_ctx, *error_string);
+                       *perror_string = talloc_steal(parent_ctx, error_string);
                }
        }
 
@@ -317,7 +325,7 @@ krb5_error_code smb_krb5_create_memory_keytab(TALLOC_CTX *parent_ctx,
        krb5_error_code ret;
        TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
        const char *rand_string;
-       const char *error_string;
+       const char *error_string = NULL;
        if (!mem_ctx) {
                return ENOMEM;
        }