From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Sun, 11 Mar 2018 18:46:23 +0000 (+0000)
Subject: Fix ldap lookups for zero-length attribute value.  Bug 2251
X-Git-Url: https://git.exim.org/users/jgh/exim.git/commitdiff_plain/fc8cd529d7801658d38d9a4fc82a8b18fe3bbcc6?hp=d9cb3c4537f82c8663c19c391bd727235916db6c

Fix ldap lookups for zero-length attribute value.  Bug 2251

Broken-by: acec9514b1
---

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 06ed2eeb5..e4ad9f0c5 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -135,6 +135,9 @@ JH/26 Bug 2253: For logging delivery lines under PRDR, append the overall
       the "C=" log element.  It can have useful tracking info from the
       destination system.  Patch from Simon Arlott.
 
+JH/27 Bug 2251: Fix ldap lookups that return a single attribute having zero-
+      length value.  Previously this would segfault.
+
 
 Exim version 4.90
 -----------------
diff --git a/src/src/lookups/ldap.c b/src/src/lookups/ldap.c
index 2ebe734cd..63c0edf79 100644
--- a/src/src/lookups/ldap.c
+++ b/src/src/lookups/ldap.c
@@ -840,13 +840,13 @@ while ((rc = ldap_result(lcp->ld, msgid, 0, timeoutptr, &result)) ==
   result = NULL;
   }            /* End "while" loop for multiple results */
 
-/* Terminate the dynamic string that we have built and reclaim unused store */
+/* Terminate the dynamic string that we have built and reclaim unused store.
+In the odd case of a single attribute with zero-length value, allocate
+an empty string. */
 
-if (data)
-  {
-  (void) string_from_gstring(data);
-  gstring_reset_unused(data);
-  }
+if (!data) data = string_get(1);
+(void) string_from_gstring(data);
+gstring_reset_unused(data);
 
 /* Copy the last dn into eldap_dn */