Lookups: fix dbmnz crash on zero-length datum. Bug 3079

[exim.git] / src / src / lookups / dbmdb.c

diff --git a/src/src/lookups/dbmdb.c b/src/src/lookups/dbmdb.c
index c99e948b59a532294e87a564ffe3874f3682e0bc..96665b6e4e68d7204b29db0e1fb16409a1b8623a 100644 (file)
--- a/src/src/lookups/dbmdb.c
+++ b/src/src/lookups/dbmdb.c
@@ -5,7 +5,7 @@
 /* Copyright (c) The Exim Maintainers 2020 - 2022 */
 /* Copyright (c) University of Cambridge 1995 - 2018 */
 /* See the file NOTICE for conditions of use and distribution. */
-/* SPDX-License-Identifier: GPL-2.0-only */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 
 #include "../exim.h"
 #include "lf_functions.h"
@@ -102,7 +102,8 @@ exim_datum_size_set(&key, length);
 
 if (exim_dbget(d, &key, &data))
   {
-  *result = string_copyn(exim_datum_data_get(&data), exim_datum_size_get(&data));
+  unsigned len = exim_datum_size_get(&data);
+  *result = len > 0 ? string_copyn(exim_datum_data_get(&data), len) : US"";
   exim_datum_free(&data);            /* Some DBM libraries need a free() call */
   return OK;
   }
@@ -283,3 +284,5 @@ static lookup_info *_lookup_list[] = { &dbm_lookup_info, &dbmz_lookup_info, &dbm
 lookup_module_info dbmdb_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 3 };
 
 /* End of lookups/dbmdb.c */
+/* vi: aw ai sw=2
+*/