1 files changed, 42 insertions, 13 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 1f85fd5c89d3..ed4ec9c30bd2 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2989,10 +2989,31 @@ 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
@@ -3005,18 +3026,7 @@ 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 "
@@ -3062,15 +3072,34 @@ static int do_init_module(struct module *mod)
 #endif
         unset_module_init_ro_nx(mod);
         module_arch_freeing_init(mod);
-        module_memfree(mod->module_init);
         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)