staging: speakup: more fixes for init-failure handling.

We still leaked many resources when Speakup failed to initialize.
Examples of leaked resources include:
/dev/synth, keyboard or VT notifiers, and heap-allocated st_spk_t
structs.
This is fixed.

* We now use PTR_ERR to detect kthread_create failure
(thank you Dan Carpenter).

* The loop which frees members of the speakup_console array now iterates
over the whole array, not stopping at the first NULL value.  Fixes
a possible memory leak.  Safe because kfree(NULL) is a no-op.

* The order of some initializations was changed.  The safe ones, which
will never fail, are performed first.
Signed-off-by: Christopher Brannon <chris@the-brannons.com>
Acked-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/speakup/main.c

@@ -1283,7 +1283,7 @@ static int edit_bits(struct vc_data *vc, u_char type, u_char ch, u_short key)
 }
 
 /* Allocation concurrency is protected by the console semaphore */
-void speakup_allocate(struct vc_data *vc)
+int speakup_allocate(struct vc_data *vc)
 {
 	int vc_num;
 
@@ -1292,10 +1292,12 @@ void speakup_allocate(struct vc_data *vc)
 		speakup_console[vc_num] = kzalloc(sizeof(*speakup_console[0]),
 						  GFP_ATOMIC);
 		if (speakup_console[vc_num] == NULL)
-			return;
+			return -ENOMEM;
 		speakup_date(vc);
 	} else if (!spk_parked)
 		speakup_date(vc);
+
+	return 0;
 }
 
 void speakup_deallocate(struct vc_data *vc)
@@ -2217,18 +2219,23 @@ static void __exit speakup_exit(void)
 {
 	int i;
 
-	free_user_msgs();
 	unregister_keyboard_notifier(&keyboard_notifier_block);
 	unregister_vt_notifier(&vt_notifier_block);
 	speakup_unregister_devsynth();
 	del_timer(&cursor_timer);
-
 	kthread_stop(speakup_task);
 	speakup_task = NULL;
 	mutex_lock(&spk_mutex);
 	synth_release();
 	mutex_unlock(&spk_mutex);
 
+	speakup_kobj_exit();
+
+	for (i = 0; i < MAX_NR_CONSOLES; i++)
+		kfree(speakup_console[i]);
+
+	speakup_remove_virtual_keyboard();
+
 	for (i = 0; i < MAXVARS; i++)
 		speakup_unregister_var(i);
 
@@ -2236,42 +2243,23 @@ static void __exit speakup_exit(void)
 		if (characters[i] != default_chars[i])
 			kfree(characters[i]);
 	}
-	for (i = 0; speakup_console[i]; i++)
-		kfree(speakup_console[i]);
-	speakup_kobj_exit();
-	speakup_remove_virtual_keyboard();
+
+	free_user_msgs();
 }
 
 /* call by: module_init() */
 static int __init speakup_init(void)
 {
 	int i;
-	int err;
+	long err = 0;
 	struct st_spk_t *first_console;
 	struct vc_data *vc = vc_cons[fg_console].d;
 	struct var_t *var;
 
-	err = speakup_add_virtual_keyboard();
-	if (err)
-		goto out;
-
+	/* These first few initializations cannot fail. */
 	initialize_msgs();	/* Initialize arrays for i18n. */
-	first_console = kzalloc(sizeof(*first_console), GFP_KERNEL);
-	if (!first_console) {
-		err = -ENOMEM;
-		goto err_cons;
-	}
-	err = speakup_kobj_init();
-	if (err)
-		goto err_kobject;
-
 	reset_default_chars();
 	reset_default_chartab();
-
-	speakup_console[vc->vc_num] = first_console;
-	speakup_date(vc);
-	pr_info("speakup %s: initialized\n", SPEAKUP_VERSION);
-
 	strlwr(synth_name);
 	spk_vars[0].u.n.high = vc->vc_cols;
 	for (var = spk_vars; var->var_id != MAXVARS; var++)
@@ -2286,31 +2274,92 @@ static int __init speakup_init(void)
 	if (quiet_boot)
 		spk_shut_up |= 0x01;
 
+	/* From here on out, initializations can fail. */
+	err = speakup_add_virtual_keyboard();
+	if (err)
+		goto error_virtkeyboard;
+
+	first_console = kzalloc(sizeof(*first_console), GFP_KERNEL);
+	if (!first_console) {
+		err = -ENOMEM;
+		goto error_alloc;
+	}
+
+	speakup_console[vc->vc_num] = first_console;
+	speakup_date(vc);
+
 	for (i = 0; i < MAX_NR_CONSOLES; i++)
-		if (vc_cons[i].d)
-			speakup_allocate(vc_cons[i].d);
+		if (vc_cons[i].d) {
+			err = speakup_allocate(vc_cons[i].d);
+			if (err)
+				goto error_kobjects;
+		}
+
+	err = speakup_kobj_init();
+	if (err)
+		goto error_kobjects;
 
-	pr_warn("synth name on entry is: %s\n", synth_name);
 	synth_init(synth_name);
 	speakup_register_devsynth();
+	/*
+	 * register_devsynth might fail, but this error is not fatal.
+	 * /dev/synth is an extra feature; the rest of Speakup
+	 * will work fine without it.
+	 */
 
-	register_keyboard_notifier(&keyboard_notifier_block);
-	register_vt_notifier(&vt_notifier_block);
+	err = register_keyboard_notifier(&keyboard_notifier_block);
+	if (err)
+		goto error_kbdnotifier;
+	err = register_vt_notifier(&vt_notifier_block);
+	if (err)
+		goto error_vtnotifier;
 
 	speakup_task = kthread_create(speakup_thread, NULL, "speakup");
-	set_user_nice(speakup_task, 10);
+
 	if (IS_ERR(speakup_task)) {
-		err = -ENOMEM;
-		goto err_kobject;
+		err = PTR_ERR(speakup_task);
+		goto error_task;
 	}
+
+	set_user_nice(speakup_task, 10);
 	wake_up_process(speakup_task);
+
+	pr_info("speakup %s: initialized\n", SPEAKUP_VERSION);
+	pr_info("synth name on entry is: %s\n", synth_name);
 	goto out;
 
-err_kobject:
-speakup_kobj_exit();
-	kfree(first_console);
-err_cons:
+error_task:
+	unregister_vt_notifier(&vt_notifier_block);
+
+error_vtnotifier:
+	unregister_keyboard_notifier(&keyboard_notifier_block);
+	del_timer(&cursor_timer);
+
+error_kbdnotifier:
+	speakup_unregister_devsynth();
+	mutex_lock(&spk_mutex);
+	synth_release();
+	mutex_unlock(&spk_mutex);
+	speakup_kobj_exit();
+
+error_kobjects:
+	for (i = 0; i < MAX_NR_CONSOLES; i++)
+		kfree(speakup_console[i]);
+
+error_alloc:
 	speakup_remove_virtual_keyboard();
+
+error_virtkeyboard:
+	for (i = 0; i < MAXVARS; i++)
+		speakup_unregister_var(i);
+
+	for (i = 0; i < 256; i++) {
+		if (characters[i] != default_chars[i])
+			kfree(characters[i]);
+	}
+
+	free_user_msgs();
+
 out:
 	return err;
 }