From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EACB3C63777 for ; Thu, 26 Nov 2020 10:48:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A96B72158C for ; Thu, 26 Nov 2020 10:48:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388395AbgKZKsb (ORCPT ); Thu, 26 Nov 2020 05:48:31 -0500 Received: from mx2.suse.de ([195.135.220.15]:58484 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729107AbgKZKsa (ORCPT ); Thu, 26 Nov 2020 05:48:30 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 123D6AC23; Thu, 26 Nov 2020 10:48:28 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 8D0C31E130F; Thu, 26 Nov 2020 11:48:27 +0100 (CET) Date: Thu, 26 Nov 2020 11:48:27 +0100 From: Jan Kara To: Borislav Petkov Cc: Jan Kara , =?utf-8?B?UGF3ZcWC?= Jasiak , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Brian Gerst , Andy Lutomirski Subject: Re: PROBLEM: fanotify_mark EFAULT on x86 Message-ID: <20201126104827.GA422@quack2.suse.cz> References: <20201101212738.GA16924@gmail.com> <20201102122638.GB23988@quack2.suse.cz> <20201103211747.GA3688@gmail.com> <20201123164622.GJ27294@quack2.suse.cz> <20201123224651.GA27809@gmail.com> <20201124084507.GA4009@zn.tnic> <20201124102033.GA19336@quack2.suse.cz> <20201124102814.GE4009@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201124102814.GE4009@zn.tnic> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue 24-11-20 11:28:14, Borislav Petkov wrote: > On Tue, Nov 24, 2020 at 11:20:33AM +0100, Jan Kara wrote: > > On Tue 24-11-20 09:45:07, Borislav Petkov wrote: > > > On Mon, Nov 23, 2020 at 11:46:51PM +0100, Paweł Jasiak wrote: > > > > On 23/11/20, Jan Kara wrote: > > > > > OK, with a help of Boris Petkov I think I have a fix that looks correct > > > > > (attach). Can you please try whether it works for you? Thanks! > > > > > > > > Unfortunately I am getting a linker error. > > > > > > > > ld: arch/x86/entry/syscall_32.o:(.rodata+0x54c): undefined reference to `__ia32_sys_ia32_fanotify_mark' > > > > > > Because CONFIG_COMPAT is not set in your .config. > > > > > > Jan, look at 121b32a58a3a and especially this hunk > > > > > > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > > > index 9b294c13809a..b8f89f78b8cd 100644 > > > --- a/arch/x86/kernel/Makefile > > > +++ b/arch/x86/kernel/Makefile > > > @@ -53,6 +53,8 @@ obj-y += setup.o x86_init.o i8259.o irqinit.o > > > obj-$(CONFIG_JUMP_LABEL) += jump_label.o > > > obj-$(CONFIG_IRQ_WORK) += irq_work.o > > > obj-y += probe_roms.o > > > +obj-$(CONFIG_X86_32) += sys_ia32.o > > > +obj-$(CONFIG_IA32_EMULATION) += sys_ia32.o > > > > > > how it enables the ia32 syscalls depending on those config items. Now, > > > you have > > > > > > #ifdef CONFIG_COMPAT > > > -COMPAT_SYSCALL_DEFINE6(fanotify_mark, > > > +SYSCALL_DEFINE6(ia32_fanotify_mark, > > > > > > which is under CONFIG_COMPAT which is not set in Paweł's config. > > > > > > config COMPAT > > > def_bool y > > > depends on IA32_EMULATION || X86_X32 > > > > > > but it depends on those two config items. > > > > > > However, it looks to me like ia32_fanotify_mark's definition should be > > > simply under CONFIG_X86_32 because: > > > > > > IA32_EMULATION is 32-bit emulation on 64-bit kernels > > > X86_X32 is for the x32 ABI > > > > Thanks for checking! I didn't realize I needed to change the ifdefs as well > > (I missed that bit in 121b32a58a3a). So do I understand correctly that > > whenever the kernel is 64-bit, 64-bit syscall args (e.g. defined as u64) are > > passed just fine regardless of whether the userspace is 32-bit or not? > > > > Also how about other 32-bit archs? Because I now realized that > > CONFIG_COMPAT as well as the COMPAT_SYSCALL_DEFINE6() is also utilized by > > other 32-bit archs (I can see a reference to compat_sys_fanotify_mark e.g. > > in sparc, powerpc, and other args). So I probably need to actually keep > > that for other archs but do the modification only for x86, don't I? > > Hmm, you raise a good point and looking at that commit again, the > intention is to supply those ia32 wrappers as both 32-bit native *and* > 32-bit emulation ones. > > So I think this > > > -#ifdef CONFIG_COMPAT > > +#if defined(CONFIG_COMPAT) || defined(CONFIG_X86_32) > > +#ifdef CONFIG_X86_32 > > +SYSCALL_DEFINE6(ia32_fanotify_mark, > > +#elif CONFIG_COMPAT > > COMPAT_SYSCALL_DEFINE6(fanotify_mark, > > +#endif > > should be > > if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) > SYSCALL_DEFINE6(ia32_fanotify_mark, > #elif CONFIG_COMPAT > COMPAT_SYSCALL_DEFINE6(fanotify_mark, > #endif > > or so. > > Meaning that 32-bit native or 32-bit emulation supplies > ia32_fanotify_mark() as a syscall wrapper and other arches doing > CONFIG_COMPAT, still do the COMPAT_SYSCALL_DEFINE6() thing. Yeah, looking again at what those config options mean I agree. Patch updated. > But I'd prefer if someone more knowledgeable than me in that whole > syscall macros muck to have a look... I'd prefer that as well but if nobody pops up, I'll just push this to my tree next week and will see what breaks :) Honza -- Jan Kara SUSE Labs, CR