From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755551Ab0K2SPx (ORCPT ); Mon, 29 Nov 2010 13:15:53 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:41319 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755321Ab0K2SPv (ORCPT ); Mon, 29 Nov 2010 13:15:51 -0500 X-Authority-Analysis: v=1.1 cv=NFUeGz0loTdi/T6hXKngYYtckjed7x3pKvNOqmBBK18= c=1 sm=0 a=qK-MKYc896kA:10 a=kj9zAlcOel0A:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=meVymXHHAAAA:8 a=7N4O53Tz1J5yzHckWZQA:9 a=Pb905KO5GJKhMdu_N1UA:7 a=XULuoXUyqyXkEwv_aO6AVk81n4gA:4 a=CjuIK1q_8ugA:10 a=jeBq3FmKZ4MA:10 a=sK8ylSXCQLFLuM5I:21 a=vYAjElNnYxOD0s2d:21 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Date: Mon, 29 Nov 2010 13:15:42 -0500 From: Steven Rostedt To: matthieu castet Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-next@vger.kernel.org, Arjan van de Ven , James Morris , Andrew Morton , Andi Kleen , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Rusty Russell , Stephen Rothwell , Dave Jones , Siarhei Liakh , Kees Cook , Peter Zijlstra Subject: Re: [PATCH 3/3 V13] RO/NX protection for loadable kernel Message-ID: <20101129181542.GA11630@home.goodmis.org> References: <4CE2F914.9070106@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CE2F914.9070106@free.fr> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch breaks function tracer: ------------[ cut here ]------------ WARNING: at kernel/trace/ftrace.c:1014 ftrace_bug+0x114/0x171() Hardware name: Precision WorkStation 470 Modules linked in: i2c_core(+) Pid: 86, comm: modprobe Not tainted 2.6.37-rc2+ #68 Call Trace: [] warn_slowpath_common+0x85/0x9d [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] warn_slowpath_null+0x1a/0x1c [] ftrace_bug+0x114/0x171 [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ftrace_process_locs+0x1ae/0x274 [] ? __process_new_adapter+0x7/0x34 [i2c_core] [] ftrace_module_notify+0x39/0x44 [] notifier_call_chain+0x37/0x63 [] __blocking_notifier_call_chain+0x46/0x5b [] blocking_notifier_call_chain+0x14/0x16 [] sys_init_module+0x73/0x1f3 [] system_call_fastpath+0x16/0x1b ---[ end trace 2aff4f4ca53ec746 ]--- ftrace faulted on writing [] __process_new_adapter+0x7/0x34 [i2c_core] On Tue, Nov 16, 2010 at 10:35:16PM +0100, matthieu castet wrote: > > @@ -2650,6 +2810,18 @@ static struct module *load_module(void __user *umod, > kfree(info.strmap); > free_copy(&info); > > + /* Set RO and NX regions for core */ > + set_section_ro_nx(mod->module_core, > + mod->core_text_size, > + mod->core_ro_size, > + mod->core_size); > + > + /* Set RO and NX regions for init */ > + set_section_ro_nx(mod->module_init, > + mod->init_text_size, > + mod->init_ro_size, > + mod->init_size); > + Here we set the text read only before we call the notifiers. The function tracer changes the calls to mcount into nops via a notifier call so this must be done after the module notifiers. > /* Done! */ > trace_module_load(mod); > return mod; > @@ -2753,6 +2925,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, > mod->symtab = mod->core_symtab; > mod->strtab = mod->core_strtab; > #endif > + unset_section_ro_nx(mod, mod->module_init); > module_free(mod, mod->module_init); > mod->module_init = NULL; > mod->init_size = 0; Below is the patch that fixes this bug. -- Steve Reported-by: Peter Zijlstra Signed-off-by: Steven Rostedt diff --git a/kernel/module.c b/kernel/module.c index ba421e6..5ccf52c 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2804,18 +2804,6 @@ static struct module *load_module(void __user *umod, kfree(info.strmap); free_copy(&info); - /* Set RO and NX regions for core */ - set_section_ro_nx(mod->module_core, - mod->core_text_size, - mod->core_ro_size, - mod->core_size); - - /* Set RO and NX regions for init */ - set_section_ro_nx(mod->module_init, - mod->init_text_size, - mod->init_ro_size, - mod->init_size); - /* Done! */ trace_module_load(mod); return mod; @@ -2876,6 +2864,18 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, blocking_notifier_call_chain(&module_notify_list, MODULE_STATE_COMING, mod); + /* Set RO and NX regions for core */ + set_section_ro_nx(mod->module_core, + mod->core_text_size, + mod->core_ro_size, + mod->core_size); + + /* Set RO and NX regions for init */ + set_section_ro_nx(mod->module_init, + mod->init_text_size, + mod->init_ro_size, + mod->init_size); + do_mod_ctors(mod); /* Start the module */ if (mod->init != NULL)