Zero length fields when freeing object contents

In krb5_free_data_contents() and krb5_free_checksum_contents(), zero
the length as well as the data pointer to leave the object in a valid
state.  Add asserts to existing test harnesses to verify the new
behavior.

In the krb5 GSS mech's kg_checksum_channel_bindings(), remove the code
to reallocate the checksum with xmalloc(), as it relied on
krb5_free_checksum_contents() leaving the object in an invalid state.
This code was added in commit a30fb4c4400f13a2690df7ef910b7ac0ccbcf194
to match an xfree() call, but commit
29337e7c7b796685fb6a03466d32147e17aa2d16 replaced that xfree() with a
krb5_free_checksum_contents().  (In addition, the xmalloc and xfree
wrappers never evolved to do anything beyond malloc and free.)

In kpropd's recv_database(), don't free outbuf until we are done using
its length.

[ghudson@mit.edu: rewrote commit message; edited doxygen comment
changes to mention version]

ticket: 8871 (new)

1 files changed, 4 insertions, 4 deletions

diff --git a/src/lib/krb5/krb/kfree.c b/src/lib/krb5/krb/kfree.c
index ab2409f..6e38044 100644
--- a/src/lib/krb5/krb/kfree.c
+++ b/src/lib/krb5/krb/kfree.c
@@ -145,6 +145,7 @@ krb5_free_checksum_contents(krb5_context context, krb5_checksum *val)
         return;
     free(val->contents);
     val->contents = NULL;
+    val->length = 0;
 }
 
 void KRB5_CALLCONV
@@ -242,10 +243,9 @@ krb5_free_data_contents(krb5_context context, krb5_data *val)
 {
     if (val == NULL)
         return;
-    if (val->data) {
-        free(val->data);
-        val->data = 0;
-    }
+    free(val->data);
+    val->data = NULL;
+    val->length = 0;
 }
 
 void KRB5_CALLCONV