diff options
Diffstat (limited to 'kernel/module.c')
| -rw-r--r-- | kernel/module.c | 91 |
1 files changed, 68 insertions, 23 deletions
diff --git a/kernel/module.c b/kernel/module.c index 3965511ae133..d856e96a3cce 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -772,9 +772,18 @@ static int try_stop_module(struct module *mod, int flags, int *forced) return 0; } -unsigned long module_refcount(struct module *mod) +/** + * module_refcount - return the refcount or -1 if unloading + * + * @mod: the module we're checking + * + * Returns: + * -1 if the module is in the process of unloading + * otherwise the number of references in the kernel to the module + */ +int module_refcount(struct module *mod) { - return (unsigned long)atomic_read(&mod->refcnt) - MODULE_REF_BASE; + return atomic_read(&mod->refcnt) - MODULE_REF_BASE; } EXPORT_SYMBOL(module_refcount); @@ -856,7 +865,7 @@ static inline void print_unload_info(struct seq_file *m, struct module *mod) struct module_use *use; int printed_something = 0; - seq_printf(m, " %lu ", module_refcount(mod)); + seq_printf(m, " %i ", module_refcount(mod)); /* * Always include a trailing , so userspace can differentiate @@ -908,7 +917,7 @@ EXPORT_SYMBOL_GPL(symbol_put_addr); static ssize_t show_refcnt(struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { - return sprintf(buffer, "%lu\n", module_refcount(mk->mod)); + return sprintf(buffer, "%i\n", module_refcount(mk->mod)); } static struct module_attribute modinfo_refcnt = @@ -1795,7 +1804,7 @@ static void unset_module_core_ro_nx(struct module *mod) { } static void unset_module_init_ro_nx(struct module *mod) { } #endif -void __weak module_free(struct module *mod, void *module_region) +void __weak module_memfree(void *module_region) { vfree(module_region); } @@ -1804,6 +1813,10 @@ void __weak module_arch_cleanup(struct module *mod) { } +void __weak module_arch_freeing_init(struct module *mod) +{ +} + /* Free a module, remove from lists, etc. */ static void free_module(struct module *mod) { @@ -1841,7 +1854,8 @@ static void free_module(struct module *mod) /* This may be NULL, but that's OK */ unset_module_init_ro_nx(mod); - module_free(mod, mod->module_init); + module_arch_freeing_init(mod); + module_memfree(mod->module_init); kfree(mod->args); percpu_modfree(mod); @@ -1850,7 +1864,7 @@ static void free_module(struct module *mod) /* Finally, free the core (containing the module structure) */ unset_module_core_ro_nx(mod); - module_free(mod, mod->module_core); + module_memfree(mod->module_core); #ifdef CONFIG_MPU update_protections(current->mm); @@ -2785,7 +2799,7 @@ static int move_module(struct module *mod, struct load_info *info) */ kmemleak_ignore(ptr); if (!ptr) { - module_free(mod, mod->module_core); + module_memfree(mod->module_core); return -ENOMEM; } memset(ptr, 0, mod->init_size); @@ -2930,8 +2944,9 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) static void module_deallocate(struct module *mod, struct load_info *info) { percpu_modfree(mod); - module_free(mod, mod->module_init); - module_free(mod, mod->module_core); + module_arch_freeing_init(mod); + module_memfree(mod->module_init); + module_memfree(mod->module_core); } int __weak module_finalize(const Elf_Ehdr *hdr, @@ -2983,10 +2998,31 @@ static void do_mod_ctors(struct module *mod) #endif } +/* For freeing module_init on success, in case kallsyms traversing */ +struct mod_initfree { + struct rcu_head rcu; + void *module_init; +}; + +static void do_free_init(struct rcu_head *head) +{ + struct mod_initfree *m = container_of(head, struct mod_initfree, rcu); + module_memfree(m->module_init); + kfree(m); +} + /* This is where the real work happens */ static int do_init_module(struct module *mod) { int ret = 0; + struct mod_initfree *freeinit; + + freeinit = kmalloc(sizeof(*freeinit), GFP_KERNEL); + if (!freeinit) { + ret = -ENOMEM; + goto fail; + } + freeinit->module_init = mod->module_init; /* * We want to find out whether @mod uses async during init. Clear @@ -2999,18 +3035,7 @@ static int do_init_module(struct module *mod) if (mod->init != NULL) ret = do_one_initcall(mod->init); if (ret < 0) { - /* - * Init routine failed: abort. Try to protect us from - * buggy refcounters. - */ - mod->state = MODULE_STATE_GOING; - synchronize_sched(); - module_put(mod); - blocking_notifier_call_chain(&module_notify_list, - MODULE_STATE_GOING, mod); - free_module(mod); - wake_up_all(&module_wq); - return ret; + goto fail_free_freeinit; } if (ret > 0) { pr_warn("%s: '%s'->init suspiciously returned %d, it should " @@ -3055,15 +3080,35 @@ static int do_init_module(struct module *mod) mod->strtab = mod->core_strtab; #endif unset_module_init_ro_nx(mod); - module_free(mod, mod->module_init); + module_arch_freeing_init(mod); mod->module_init = NULL; mod->init_size = 0; mod->init_ro_size = 0; mod->init_text_size = 0; + /* + * We want to free module_init, but be aware that kallsyms may be + * walking this with preempt disabled. In all the failure paths, + * we call synchronize_rcu/synchronize_sched, but we don't want + * to slow down the success path, so use actual RCU here. + */ + call_rcu(&freeinit->rcu, do_free_init); mutex_unlock(&module_mutex); wake_up_all(&module_wq); return 0; + +fail_free_freeinit: + kfree(freeinit); +fail: + /* Try to protect us from buggy refcounters. */ + mod->state = MODULE_STATE_GOING; + synchronize_sched(); + module_put(mod); + blocking_notifier_call_chain(&module_notify_list, + MODULE_STATE_GOING, mod); + free_module(mod); + wake_up_all(&module_wq); + return ret; } static int may_init_module(void) |