From 6e2b75740bed35df98b8113300579e13ed2ce848 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 16 Mar 2009 18:13:36 -0400 Subject: [PATCH] module: fix refptr allocation and release order Impact: fix ref-after-free crash on failed module load Fix refptr bug: Change refptr allocation and release order not to access a module data structure pointed by 'mod' after freeing mod->module_core. This bug will cause kernel panic(e.g. failed to find undefined symbols). This bug was reported on systemtap bugzilla. http://sources.redhat.com/bugzilla/show_bug.cgi?id=9927 Signed-off-by: Masami Hiramatsu Cc: Eric Dumazet Signed-off-by: Rusty Russell --- kernel/module.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index ba22484a987e..1196f5d11700 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2015,14 +2015,6 @@ static noinline struct module *load_module(void __user *umod, if (err < 0) goto free_mod; -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), - mod->name); - if (!mod->refptr) { - err = -ENOMEM; - goto free_mod; - } -#endif if (pcpuindex) { /* We have a special allocation for this section. */ percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size, @@ -2030,7 +2022,7 @@ static noinline struct module *load_module(void __user *umod, mod->name); if (!percpu) { err = -ENOMEM; - goto free_percpu; + goto free_mod; } sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC; mod->percpu = percpu; @@ -2082,6 +2074,14 @@ static noinline struct module *load_module(void __user *umod, /* Module has been moved. */ mod = (void *)sechdrs[modindex].sh_addr; +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), + mod->name); + if (!mod->refptr) { + err = -ENOMEM; + goto free_init; + } +#endif /* Now we've moved module, initialize linked lists, etc. */ module_unload_init(mod); @@ -2288,15 +2288,17 @@ static noinline struct module *load_module(void __user *umod, ftrace_release(mod->module_core, mod->core_size); free_unload: module_unload_free(mod); + free_init: +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + percpu_modfree(mod->refptr); +#endif module_free(mod, mod->module_init); free_core: module_free(mod, mod->module_core); + /* mod will be freed with core. Don't access it beyond this line! */ free_percpu: if (percpu) percpu_modfree(percpu); -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - percpu_modfree(mod->refptr); -#endif free_mod: kfree(args); free_hdr: -- 2.20.1