From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751071AbdEaDtZ (ORCPT ); Tue, 30 May 2017 23:49:25 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:6837 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751032AbdEaDtY (ORCPT ); Tue, 30 May 2017 23:49:24 -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> CC: , Xie XiuQi , , , , , , From: Wanlong Gao Message-ID: Date: Wed, 31 May 2017 11:48:56 +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: <20170531033042.mtrmcj6odvn2bmxs@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=0001.0A010206.592E3D40.002A,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: dcb89d5b0eb68f7457d397cab7f66927 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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) Thanks, Wanlong Gao > > 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 >>>> >>> >>> . >>> >> > > . >