[gnome-keyring] Don't leak password data in gkm_wrap_prompt_do_credential

[Stefan Walter <stefw src gnome org>]

commit b087539a6cdd624fc4e0d6ae7de2811ab96864e6
Author: Christophe Fergeau <cfergeau redhat com>
Date:   Sun Sep 21 18:46:04 2014 +0200

    Don't leak password data in gkm_wrap_prompt_do_credential
    
    Memory returned by auto_unlock_lookup_object() must be freed
    while memory returned by gkm_wrap_prompt_request_password() must
    not be freed. Depending on the situation, CredentialPrompt::password
    will contain one or the other, and currently this field is never
    freed, causing leaks when the password comes from
    auto_unlock_lookup_object().
    
    This commit will always free CredentialPrompt::password when it's
    no longer needed, and will create a copy of the returned string
    when gkm_wrap_prompt_request_password() is called.
    
    This fixes (line numbers from 3.13.91-2-g45bb5be):
    
    ==2190== 8 bytes in 1 blocks are definitely lost in loss record 58 of 1,294
    ==2190==    at 0x4A0645D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==2190==    by 0x5DE6DE6: g_malloc (gmem.c:97)
    ==2190==    by 0x5E024B5: g_memdup (gstrfuncs.c:384)
    ==2190==    by 0x41296C: gkm_template_set (gkm-attributes.c:600)
    ==2190==    by 0x4129F0: gkm_template_set_value (gkm-attributes.c:614)
    ==2190==    by 0x419BCD: mock_secret_C_CreateObject (mock-secret-store.c:174)
    ==2190==    by 0x40646E: wrap_C_CreateObject (gkm-wrap-layer.c:741)
    ==2190==    by 0x418985: find_login_keyring_item (gkm-wrap-login.c:254)
    ==2190==    by 0x4190AF: gkm_wrap_login_lookup_secret (gkm-wrap-login.c:396)
    ==2190==    by 0x407E8D: auto_unlock_lookup_object (gkm-wrap-prompt.c:198)
    ==2190==    by 0x40B9B0: login_prompt_do_specific (gkm-wrap-prompt.c:1453)
    ==2190==    by 0x40C13A: gkm_wrap_prompt_do_login (gkm-wrap-prompt.c:1591)
    ==2190==    by 0x406384: auth_C_Login (gkm-wrap-layer.c:706)
    ==2190==    by 0x40472A: test_specific (test-login-auto.c:156)
    ==2190==    by 0x5E0A27A: test_case_run (gtestutils.c:2059)
    ==2190==    by 0x5E0A602: g_test_run_suite_internal (gtestutils.c:2120)
    ==2190==    by 0x5E0A6C4: g_test_run_suite_internal (gtestutils.c:2131)
    ==2190==    by 0x5E0A6C4: g_test_run_suite_internal (gtestutils.c:2131)
    ==2190==    by 0x5E0A847: g_test_run_suite (gtestutils.c:2184)
    ==2190==    by 0x5E09551: g_test_run (gtestutils.c:1488)
    ==2190==    by 0x410851: testing_thread (egg-testing.c:142)
    ==2190==    by 0x5E0D2F4: g_thread_proxy (gthread.c:764)
    ==2190==    by 0x3B7AE07F34: start_thread (pthread_create.c:309)
    ==2190==    by 0x3B7AAF4C3C: clone (clone.S:111)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=738508

 pkcs11/wrap-layer/gkm-wrap-prompt.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/pkcs11/wrap-layer/gkm-wrap-prompt.c b/pkcs11/wrap-layer/gkm-wrap-prompt.c
index 5b86d1d..3d3d4f5 100644
--- a/pkcs11/wrap-layer/gkm-wrap-prompt.c
+++ b/pkcs11/wrap-layer/gkm-wrap-prompt.c
@@ -950,7 +950,7 @@ gkm_wrap_prompt_class_init (GkmWrapPromptClass *klass)
 typedef struct _CredentialPrompt {
        GArray *template;
        CK_ULONG n_template;
-       const gchar *password;
+       gchar *password;
 } CredentialPrompt;
 
 static void
@@ -958,6 +958,7 @@ credential_prompt_free (gpointer user_data)
 {
        CredentialPrompt *data = user_data;
        g_array_free (data->template, TRUE);
+       egg_secure_strfree (data->password);
        g_slice_free (CredentialPrompt, data);
 }
 
@@ -1033,6 +1034,7 @@ gkm_wrap_prompt_do_credential (GkmWrapPrompt *self, CK_ATTRIBUTE_PTR *template,
        attrs = get_attributes_from_object (self, &n_attrs);
        g_return_val_if_fail (attrs, FALSE);
 
+       egg_secure_strfree (data->password);
        data->password = NULL;
 
        if (self->iteration == 0) {
@@ -1044,6 +1046,7 @@ gkm_wrap_prompt_do_credential (GkmWrapPrompt *self, CK_ATTRIBUTE_PTR *template,
        }
 
        if (!data->password) {
+               const char *password;
                setup_unlock_prompt (self, attrs, n_attrs, self->iteration == 1);
 
                /* Now load up the unlock options into the prompt*/
@@ -1055,14 +1058,15 @@ gkm_wrap_prompt_do_credential (GkmWrapPrompt *self, CK_ATTRIBUTE_PTR *template,
 
                ++(self->iteration);
 
-               data->password = gkm_wrap_prompt_request_password (self);
-               if (data->password == NULL) {
+               password = gkm_wrap_prompt_request_password (self);
+               if (password == NULL) {
                        if (error != NULL) {
                                g_warning ("couldn't prompt for password: %s", egg_error_message (error));
                                g_error_free (error);
                        }
                        return FALSE;
                }
+               data->password = egg_secure_strdup (password);
        }
 
        /* Truncate any extra options off the end of template */