CVE-2010-1322 KDC uninitialized pointer crash in authorization data handling (MITKRB5...

When the KDC receives certain TGS-REQ messages, it may dereference an
uninitialized pointer while processing authorization data, causing a
crash, or in rare cases, unauthorized information disclosure, ticket
modification, or execution of arbitrary code.  The crash may be
triggered by legitimate requests.

Correctly implement the filtering of authorization data items to avoid
leaving uninitialized pointers when omitting items.

ticket: 6797
tags: pullup
target_version: 1.8.4

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24429 dc483132-0cff-0310-8789-dd5450dbe970

diff --git a/src/kdc/kdc_authdata.c b/src/kdc/kdc_authdata.c
index fa6a72e392173a0f08792cd93be5bfc1fee09b36..a4f81a60a2c7eeac3a1b6f5ebe3381c3685982e1 100644 (file)
--- a/src/kdc/kdc_authdata.c
+++ b/src/kdc/kdc_authdata.c
@@ -495,7 +495,7 @@ merge_authdata (krb5_context context,
                 krb5_boolean copy,
                 krb5_boolean ignore_kdc_issued)
 {
-    size_t i, nadata = 0;
+    size_t i, j, nadata = 0;
     krb5_authdata **authdata = *out_authdata;
 
     if (in_authdata == NULL || in_authdata[0] == NULL)
@@ -529,16 +529,16 @@ merge_authdata (krb5_context context,
         in_authdata = tmp;
     }
 
-    for (i = 0; in_authdata[i] != NULL; i++) {
+    for (i = 0, j = 0; in_authdata[i] != NULL; i++) {
         if (ignore_kdc_issued &&
             is_kdc_issued_authdatum(context, in_authdata[i], 0)) {
             free(in_authdata[i]->contents);
             free(in_authdata[i]);
         } else
-            authdata[nadata + i] = in_authdata[i];
+            authdata[nadata + j++] = in_authdata[i];
     }
 
-    authdata[nadata + i] = NULL;
+    authdata[nadata + j] = NULL;
 
     free(in_authdata);