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

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 5b86d1d7..3d3d4f57 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 */