s4:dsdb Fix use of memory after free in repl_meta_data

The upgraded link values are were allocated on tmp_ctx, and need to be
kept until they are written to the DB.  If we don't give the correct
context, they will be gone after the talloc_free(tmp_ctx).

Found by Matthieu Patou <mat+Informatique.Samba@matws.net>

Andrew Bartlett

diff --git a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
index 1814b70f2c7e51985e5815abd19190560b98446c..11e043f5d0931b9639f84c1e39b46628d083327e 100644 (file)
--- a/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
+++ b/source4/dsdb/samdb/ldb_modules/repl_meta_data.c
@@ -1407,8 +1407,10 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct d
 
 /*
   check if any links need upgrading from w2k format
+
+  The parent_ctx is the ldb_message_element which contains the values array that dns[i].v points at, and which should be used for allocating any new value.
  */
-static int replmd_check_upgrade_links(struct parsed_dn *dns, uint32_t count, const struct GUID *invocation_id)
+static int replmd_check_upgrade_links(struct parsed_dn *dns, uint32_t count, struct ldb_message_element *parent_ctx, const struct GUID *invocation_id)
 {
        uint32_t i;
        for (i=0; i<count; i++) {
@@ -1422,7 +1424,7 @@ static int replmd_check_upgrade_links(struct parsed_dn *dns, uint32_t count, con
                }
 
                /* it's an old one that needs upgrading */
-               ret = replmd_update_la_val(dns, dns[i].v, dns[i].dsdb_dn, dns[i].dsdb_dn, invocation_id,
+               ret = replmd_update_la_val(parent_ctx->values, dns[i].v, dns[i].dsdb_dn, dns[i].dsdb_dn, invocation_id,
                                           1, 1, 0, 0, false);
                if (ret != LDB_SUCCESS) {
                        return ret;
@@ -1574,8 +1576,8 @@ static int replmd_modify_la_add(struct ldb_module *module,
                talloc_free(tmp_ctx);
                return LDB_ERR_OPERATIONS_ERROR;
        }
-
-       ret = replmd_check_upgrade_links(old_dns, old_num_values, invocation_id);
+       
+       ret = replmd_check_upgrade_links(old_dns, old_num_values, old_el, invocation_id);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
@@ -1700,7 +1702,7 @@ static int replmd_modify_la_delete(struct ldb_module *module,
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = replmd_check_upgrade_links(old_dns, old_el->num_values, invocation_id);
+       ret = replmd_check_upgrade_links(old_dns, old_el->num_values, old_el, invocation_id);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
@@ -1818,7 +1820,7 @@ static int replmd_modify_la_replace(struct ldb_module *module,
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = replmd_check_upgrade_links(old_dns, old_num_values, invocation_id);
+       ret = replmd_check_upgrade_links(old_dns, old_num_values, old_el, invocation_id);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
@@ -3693,7 +3695,7 @@ linked_attributes[0]:
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = replmd_check_upgrade_links(pdn_list, old_el->num_values, our_invocation_id);
+       ret = replmd_check_upgrade_links(pdn_list, old_el->num_values, old_el, our_invocation_id);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;