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 814a5df0238115de05b4178026fc143e1c61192c..020dc33d7ca8074bdf00fb95b6c09cfc68771d4d 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;
                     }