digest_edirectory_auth: improved error handling

Malicious response from LDAP server can cause squid helper to crash.

Missing realm value returned from LDAP without error/missing value being
indicated in the response can lead to strcmp() using a NULL pointer.
 Extremely unlikely to happen in practice, but worth fixing.

 Detected by Coverity Scan. Issue 740399

diff --git a/helpers/digest_auth/eDirectory/ldap_backend.cc b/helpers/digest_auth/eDirectory/ldap_backend.cc
index e7deefc258717a194a5da085d9f59fa9be1cc4f4..0ce4fb82ce18477a71891d996670b4149e3baed8 100644 (file)
--- a/helpers/digest_auth/eDirectory/ldap_backend.cc
+++ b/helpers/digest_auth/eDirectory/ldap_backend.cc
@@ -286,7 +286,8 @@ retrydnattr:
             value = values;
             while (*value) {
                 if (encrpass) {
-                    if (strcmp(strtok(*value, delimiter), realm) == 0) {
+                    const char *t = strtok(*value, delimiter);
+                    if (t && strcmp(t, realm) == 0) {
                         password = strtok(NULL, delimiter);
                         break;
                     }