krb5 commit: Fix bugs in previous cc_file.c changes

[Greg Hudson]

https://github.com/krb5/krb5/commit/14f039b40efd91b93b1148765bf0b7d3c90db58a
commit 14f039b40efd91b93b1148765bf0b7d3c90db58a
Author: Greg Hudson <ghudson at mit.edu>
Date:   Tue Dec 16 12:57:56 2014 -0500

    Fix bugs in previous cc_file.c changes
    
    In fcc_destroy and krb5int_fcc_new_unique, call set_errmsg_filename
    before deleting the cache handle, or else the reference to
    data->filename is a use after free.
    
    In set_errmsg_filename, do nothing if the code is 0, as we don't have
    an error to annotate.
    
    ticket: 8052

 src/lib/krb5/ccache/cc_file.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/lib/krb5/ccache/cc_file.c b/src/lib/krb5/ccache/cc_file.c
index de9c968..6789c09 100644
--- a/src/lib/krb5/ccache/cc_file.c
+++ b/src/lib/krb5/ccache/cc_file.c
@@ -117,6 +117,8 @@ static krb5_error_code
 set_errmsg_filename(krb5_context context, krb5_error_code ret,
                     const char *fname)
 {
+    if (!ret)
+        return 0;
     k5_setmsg(context, ret, "%s (filename: %s)", error_message(ret), fname);
     return ret;
 }
@@ -644,12 +646,13 @@ fcc_destroy(krb5_context context, krb5_ccache id)
 #endif /* MSDOS_FILESYSTEM */
 
 cleanup:
+    (void)set_errmsg_filename(context, ret, data->filename);
     k5_cc_mutex_unlock(context, &data->lock);
     free_fccdata(context, data);
     free(id);
 
     krb5_change_cache();
-    return set_errmsg_filename(context, ret, data->filename);
+    return ret;
 }
 
 extern const krb5_cc_ops krb5_fcc_ops;
@@ -893,11 +896,12 @@ krb5int_fcc_new_unique(krb5_context context, char *template, krb5_ccache *id)
     return 0;
 
 err_out:
+    (void)set_errmsg_filename(context, ret, data->filename);
     k5_cc_mutex_unlock(context, &data->lock);
     k5_cc_mutex_destroy(&data->lock);
     free(data->filename);
     free(data);
-    return set_errmsg_filename(context, ret, data->filename);
+    return ret;
 }
 
 /*