module: Fix freeing of charp module parameters when CONFIG_SYSFS=n

When setting a charp module parameter, the param_set_charp() function
allocates memory to store a copy of the input value. Later, when the module
is potentially unloaded, the destroy_params() function is called to free
this allocated memory.

However, destroy_params() is available only when CONFIG_SYSFS=y, otherwise
only a dummy variant is present. In the unlikely case that the kernel is
configured with CONFIG_MODULES=y and CONFIG_SYSFS=n, this results in
a memory leak of charp values when a module is unloaded.

Fix this issue by making destroy_params() always available when
CONFIG_MODULES=y. Rename the function to module_destroy_params() to clarify
that it is intended for use by the module loader.

Fixes: e180a6b775 ("param: fix charp parameters set via sysfs")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

kernel/module/main.c

@@ -1408,7 +1408,7 @@ static void free_module(struct module *mod)
 	module_unload_free(mod);
 
 	/* Free any allocated parameters. */
-	destroy_params(mod->kp, mod->num_kp);
+	module_destroy_params(mod->kp, mod->num_kp);
 
 	if (is_livepatch_module(mod))
 		free_module_elf(mod);
@@ -3519,7 +3519,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	mod_sysfs_teardown(mod);
  coming_cleanup:
 	mod->state = MODULE_STATE_GOING;
-	destroy_params(mod->kp, mod->num_kp);
+	module_destroy_params(mod->kp, mod->num_kp);
 	blocking_notifier_call_chain(&module_notify_list,
 				     MODULE_STATE_GOING, mod);
 	klp_module_going(mod);