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)