Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751185AbdFBDoo (ORCPT ); Thu, 1 Jun 2017 23:44:44 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:6937 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751135AbdFBDon (ORCPT ); Thu, 1 Jun 2017 23:44:43 -0400 Subject: Re: [PATCH] modpost: abort if a module name is too long To: Jessica Yu References: <1495266381-14755-1-git-send-email-xiexiuqi@huawei.com> <20170529091007.e3zhsasmcxhzexx6@jeyu> <20170531033042.mtrmcj6odvn2bmxs@jeyu> <20170601232303.qtc6eldvl6xh2ln6@jeyu> <61160239-31e2-8bfe-766b-4570922c0726@huawei.com> CC: , Xie XiuQi , , , , , , From: Wanlong Gao Message-ID: <62512ecf-ff26-e0ad-a2e8-3dd683aa514d@huawei.com> Date: Fri, 2 Jun 2017 11:44:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <61160239-31e2-8bfe-766b-4570922c0726@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.97.93] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.5930DF29.007A,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: a3ae41406b1187dd4d5939d479ac63be Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6094 Lines: 183 On 2017/6/2 11:04, Wanlong Gao wrote: > > > On 2017/6/2 7:23, Jessica Yu wrote: >> +++ Wanlong Gao [31/05/17 11:48 +0800]: >>> >>> >>> On 2017/5/31 11:30, Jessica Yu wrote: >>>> +++ Wanlong Gao [31/05/17 10:23 +0800]: >>>>> Hi Jessica, >>>>> >>>>> On 2017/5/29 17:10, Jessica Yu wrote: >>>>>> +++ Xie XiuQi [20/05/17 15:46 +0800]: >>>>>>> From: Wanlong Gao >>>>>>> >>>>>>> Module name has a limited length, but currently the build system >>>>>>> allows the build finishing even if the module name is too long. >>>>>>> >>>>>>> CC /root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.o >>>>>>> /root/kprobe_example/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.c:9:2: >>>>>>> warning: initializer-string for array of chars is too long [enabled by default] >>>>>>> .name = KBUILD_MODNAME, >>>>>>> ^ >>>>>>> >>>>>>> but it's merely a warning. >>>>>>> >>>>>>> This patch adds the check of the module name length in modpost and stops >>>>>>> the build properly. >>>>>>> >>>>>>> Signed-off-by: Wanlong Gao >>>>>>> Signed-off-by: Xie XiuQi >>>>>>> --- >>>>>>> scripts/mod/modpost.c | 11 +++++++++++ >>>>>>> 1 file changed, 11 insertions(+) >>>>>>> >>>>>>> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c >>>>>>> index 30d752a..db11c57 100644 >>>>>>> --- a/scripts/mod/modpost.c >>>>>>> +++ b/scripts/mod/modpost.c >>>>>>> @@ -2166,6 +2166,17 @@ static int add_versions(struct buffer *b, struct module *mod) >>>>>>> { >>>>>>> struct symbol *s, *exp; >>>>>>> int err = 0; >>>>>>> + const char *mod_name; >>>>>>> + >>>>>>> + mod_name = strrchr(mod->name, '/'); >>>>>>> + if (mod_name == NULL) >>>>>>> + mod_name = mod->name; >>>>>>> + else >>>>>>> + mod_name++; >>>>>>> + if (strlen(mod_name) >= MODULE_NAME_LEN) { >>>>>>> + merror("module name is too long [%s.ko]\n", mod->name); >>>>>>> + return 1; >>>>>>> + } >>>>>> >>>>>> Hi Xie, >>>>>> >>>>>> This check shouldn't be in add_versions() (which does something else entirely), >>>>>> it should probably be put in a separate helper function called from main. But >>>>>> I'm not a big fan of the extra string manipulation to do something this simple. >>>>>> >>>>>> I think this check can be vastly simplified, how about something like the >>>>>> following? >>>>> >>>>> This looks better, would you apply your following patch? >>>>> >>>>> Reviewed-by: Wanlong Gao >>>>> Tested-by: Wanlong Gao >>>> >>>> Sure, thanks for testing. I'll go ahead and format this into a proper >>>> patch and resend. >>> >>> Please wait, I just found that this patch makes the built module can't >>> be inserted by the following error: >>> >>> # insmod abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabc.ko >>> insmod: ERROR: could not insert module abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabc.ko: Invalid parameters >>> >>> # dmesg >>> abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabc: Unknown symbol __fentry__ (err -22) >> >> Hm, I am unable to reproduce this. It looks like __fentry__ is missing >> from your kernel, you may have a mismatch between the kernel config >> that you're running and the config you are using to build the module. >> In other words, it seems like you might have built the module with >> CONFIG_FTRACE but built the kernel without. >> >> Few questions - >> >> What is the output of running `grep __fentry__ /proc/kallsyms`? >> > > Sure it has. > >> Does your module correspond to the running kernel version? > > Sure. > >> >> Do you have CONFIG_FTRACE/FUNCTION_TRACER enabled in your running >> kernel? >> > > Sure. > > >> Is that the full dmesg output (are there any other error messages)? > > Even when I compiled the kernel with your patch, the kernel module load > failed at the boot time with the following error: > > [ 1.656708] libcrc32c: no symbol version for __fentry__ > [ 1.656709] libcrc32c: Unknown symbol __fentry__ (err -22) > > But my above patch in add_versions() doesn't have such problem, I've no > idea why. Maybe your patch breaks some sections? And FYI, if I removed the "used" in attribute, this problem goes away, the compiled module can be inserted without error. expect that there is a "_modname_test defined but not used" warning: CC /root/kprobe_example_abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.o /root/kprobe_example_abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz/abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz.mod.c:18:38: warning: ?__modname_test? defined but not used [-Wunused-function] __attribute__((section(".discard"))) __modname_test(void) Any idea? Thanks, Wanlong Gao > > Thanks, > Wanlong Gao > >> >> Thanks, >> >> Jessica >> >>>>>> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c >>>>>> index 48397fe..bb09fc7 100644 >>>>>> --- a/scripts/mod/modpost.c >>>>>> +++ b/scripts/mod/modpost.c >>>>>> @@ -2139,6 +2139,9 @@ static void add_header(struct buffer *b, struct module *mod) >>>>>> "#endif\n"); >>>>>> buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n"); >>>>>> buf_printf(b, "};\n"); >>>>>> + buf_printf(b, "\n"); >>>>>> + buf_printf(b, "static void __attribute__((section(\".discard\"), used)) __modname_test(void)\n"); >>>>>> + buf_printf(b, "{ BUILD_BUG_ON(sizeof(KBUILD_MODNAME) > MODULE_NAME_LEN); }\n"); >>>>>> } >>>>>> >>>>>> static void add_intree_flag(struct buffer *b, int is_intree) >>>>>> >>>>>> This simply checks if KBUILD_MODNAME > MODULE_NAME_LEN and breaks the build if >>>>>> it does. >>>>>> >>>>>> Jessica >>>>>> >>>>>>> for (s = mod->unres; s; s = s->next) { >>>>>>> exp = find_symbol(s->name); >>>>>>> -- >>>>>>> 1.8.3.1 >>>>>>> >>>>>> >>>>>> . >>>>>> >>>>> >>>> >>>> . >>>> >>> >> >> . >> > > > . >