Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751161AbdFBDFH (ORCPT ); Thu, 1 Jun 2017 23:05:07 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:6936 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751122AbdFBDFG (ORCPT ); Thu, 1 Jun 2017 23:05:06 -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> CC: , Xie XiuQi , , , , , , From: Wanlong Gao Message-ID: <61160239-31e2-8bfe-766b-4570922c0726@huawei.com> Date: Fri, 2 Jun 2017 11:04:08 +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: <20170601232303.qtc6eldvl6xh2ln6@jeyu> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.97.93] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.5930D5DF.01DD,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: 5125 Lines: 160 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? 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 >>>>>> >>>>> >>>>> . >>>>> >>>> >>> >>> . >>> >> > > . >