From eb58cafce36423ece63a4c1b503a965b38527171 Mon Sep 17 00:00:00 2001

From: Robbie Harwood <rharwood@redhat.com>

Date: Wed, 18 Apr 2018 14:13:28 -0400

Subject: [PATCH] Fix segfault in finish_dispatch()

dispatch() doesn't necessarily initialize state->active_realm which

led to an explicit NULL dereference in finish_dispatch().

Additionally, fix make_too_big_error() so that it won't subsequently

dereference state->active_realm.

tags: pullup

target_version: 1.16-next

target_version: 1.15-next

(cherry picked from commit c822bacc1b33970a2a20d9eae80f43307e783516)

---

 src/kdc/dispatch.c | 79 ++++++++++++++++++++++++----------------------

 1 file changed, 42 insertions(+), 37 deletions(-)

diff --git a/src/kdc/dispatch.c b/src/kdc/dispatch.c

index 4ecc23481..1f4b70874 100644

--- a/src/kdc/dispatch.c

+++ b/src/kdc/dispatch.c

@@ -35,9 +35,6 @@

 static krb5_int32 last_usec = 0, last_os_random = 0;

-static krb5_error_code make_too_big_error(kdc_realm_t *kdc_active_realm,

-                                          krb5_data **out);

-

 struct dispatch_state {

     loop_respond_fn respond;

     void *arg;

@@ -47,6 +44,41 @@ struct dispatch_state {

     krb5_context kdc_err_context;

 };

+

+static krb5_error_code

+make_too_big_error(krb5_context context, krb5_principal tgsprinc,

+                   krb5_data **out)

+{

+    krb5_error errpkt;

+    krb5_error_code retval;

+    krb5_data *scratch;

+

+    *out = NULL;

+    memset(&errpkt, 0, sizeof(errpkt));

+

+    retval = krb5_us_timeofday(context, &errpkt.stime, &errpkt.susec);

+    if (retval)

+        return retval;

+    errpkt.error = KRB_ERR_RESPONSE_TOO_BIG;

+    errpkt.server = tgsprinc;

+    errpkt.client = NULL;

+    errpkt.text.length = 0;

+    errpkt.text.data = 0;

+    errpkt.e_data.length = 0;

+    errpkt.e_data.data = 0;

+    scratch = malloc(sizeof(*scratch));

+    if (scratch == NULL)

+        return ENOMEM;

+    retval = krb5_mk_error(context, &errpkt, scratch);

+    if (retval) {

+        free(scratch);

+        return retval;

+    }

+

+    *out = scratch;

+    return 0;

+}

+

 static void

 finish_dispatch(struct dispatch_state *state, krb5_error_code code,

                 krb5_data *response)

@@ -54,12 +86,17 @@ finish_dispatch(struct dispatch_state *state, krb5_error_code code,

     loop_respond_fn oldrespond = state->respond;

     void *oldarg = state->arg;

     kdc_realm_t *kdc_active_realm = state->active_realm;

+    krb5_principal tgsprinc = NULL;

+

+    if (kdc_active_realm != NULL)

+        tgsprinc = kdc_active_realm->realm_tgsprinc;

     if (state->is_tcp == 0 && response &&

         response->length > (unsigned int)max_dgram_reply_size) {

-        krb5_free_data(kdc_context, response);

+        krb5_free_data(state->kdc_err_context, response);

         response = NULL;

-        code = make_too_big_error(kdc_active_realm, &response);

+        code = make_too_big_error(state->kdc_err_context, tgsprinc,

+                                  &response);

         if (code)

             krb5_klog_syslog(LOG_ERR, "error constructing "

                              "KRB_ERR_RESPONSE_TOO_BIG error: %s",

@@ -201,38 +238,6 @@ dispatch(void *cb, struct sockaddr *local_saddr,

     finish_dispatch_cache(state, retval, response);

 }

-static krb5_error_code

-make_too_big_error(kdc_realm_t *kdc_active_realm, krb5_data **out)

-{

-    krb5_error errpkt;

-    krb5_error_code retval;

-    krb5_data *scratch;

-

-    *out = NULL;

-    memset(&errpkt, 0, sizeof(errpkt));

-

-    retval = krb5_us_timeofday(kdc_context, &errpkt.stime, &errpkt.susec);

-    if (retval)

-        return retval;

-    errpkt.error = KRB_ERR_RESPONSE_TOO_BIG;

-    errpkt.server = tgs_server;

-    errpkt.client = NULL;

-    errpkt.text.length = 0;

-    errpkt.text.data = 0;

-    errpkt.e_data.length = 0;

-    errpkt.e_data.data = 0;

-    scratch = malloc(sizeof(*scratch));

-    if (scratch == NULL)

-        return ENOMEM;

-    retval = krb5_mk_error(kdc_context, &errpkt, scratch);

-    if (retval) {

-        free(scratch);

-        return retval;

-    }

-

-    *out = scratch;

-    return 0;

-}

 krb5_context get_context(void *handle)

 {