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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E31EBC36010 for ; Tue, 8 Apr 2025 22:36:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=2cOyXdxaCm7uzvDsWtUl+FYSlRBXmDs1eFlCpFc6ohc=; b=jHG3HOFl18LAue 0/KaGTbqFHbl1pwBEw2bqQfFQvapCy1e8TvdyWYCS50FuqH0JGuwiSsjfjRrGCTotPbU/txFLwYOS EWeVhpHTmUickBivVzgV3YRjhBsU3kdiFISfUno4guWPwC2yESc64QSG9ToNKKJeii7o+lX4LnAOo 3y5lMB09ygSDaUqjznWD0bAS6DZxUCJ2i0+5Dhi3iugDbQQsLK5MS3tK0Yg7dZj09W5ra7ZUj8PWm j6R+gggmvoGCsqwIj16f+iVroMMXkq2O9Z1I1pAcfnFH2e3mESkY0dExX8oIWl43l4fWI6/Zd3GoW 1A0ukZSEqp+EgHgpPFqw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2HYK-00000005bDW-0x17; Tue, 08 Apr 2025 22:36:20 +0000 Received: from vmicros1.altlinux.org ([194.107.17.57]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2HYG-00000005bD5-2miF for linux-riscv@lists.infradead.org; Tue, 08 Apr 2025 22:36:19 +0000 Received: from mua.local.altlinux.org (mua.local.altlinux.org [192.168.1.14]) by vmicros1.altlinux.org (Postfix) with ESMTP id 0DEF672C8CC; Wed, 9 Apr 2025 01:36:12 +0300 (MSK) Received: by mua.local.altlinux.org (Postfix, from userid 508) id 0053E7CCB3A; Wed, 9 Apr 2025 01:36:11 +0300 (IDT) Date: Wed, 9 Apr 2025 01:36:11 +0300 From: "Dmitry V. Levin" To: Nathan Chancellor Cc: Andrew Morton , Oleg Nesterov , Charlie Jenkins , Arnd Bergmann , strace-devel@lists.strace.io, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v7 2/6] syscall.h: add syscall_set_arguments() Message-ID: <20250408223611.GA26876@strace.io> References: <20250303111910.GA24170@strace.io> <20250303112009.GC24170@strace.io> <20250408213131.GA2872426@ax162> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20250408213131.GA2872426@ax162> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250408_153617_031735_FDDF7BA6 X-CRM114-Status: GOOD ( 28.92 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Hi Nathan, On Tue, Apr 08, 2025 at 02:31:31PM -0700, Nathan Chancellor wrote: > Hi Dmitry, > > [dropping majority of folks since this seems irrelevant to them] > > On Mon, Mar 03, 2025 at 01:20:09PM +0200, Dmitry V. Levin wrote: > > This function is going to be needed on all HAVE_ARCH_TRACEHOOK > > architectures to implement PTRACE_SET_SYSCALL_INFO API. > > > > This partially reverts commit 7962c2eddbfe ("arch: remove unused > > function syscall_set_arguments()") by reusing some of old > > syscall_set_arguments() implementations. > > > > Signed-off-by: Dmitry V. Levin > > Tested-by: Charlie Jenkins > > Reviewed-by: Charlie Jenkins > > Acked-by: Helge Deller # parisc > > Reviewed-by: Maciej W. Rozycki # mips > ... > > diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h > > index 121fff429dce..8d389ba995c8 100644 > > --- a/arch/riscv/include/asm/syscall.h > > +++ b/arch/riscv/include/asm/syscall.h > > @@ -66,6 +66,15 @@ static inline void syscall_get_arguments(struct task_struct *task, > > memcpy(args, ®s->a1, 5 * sizeof(args[0])); > > } > > > > +static inline void syscall_set_arguments(struct task_struct *task, > > + struct pt_regs *regs, > > + const unsigned long *args) > > +{ > > + regs->orig_a0 = args[0]; > > + args++; > > + memcpy(®s->a1, args, 5 * sizeof(regs->a1)); > > +} > > This upsets the compiletime fortify checks, as I see a warning after > syscall_set_arguments() starts being used in kernel/ptrace.c later in > the series. > > $ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux- allmodconfig kernel/ptrace.o > In file included from include/linux/string.h:392, > from include/linux/bitmap.h:13, > from include/linux/cpumask.h:12, > from arch/riscv/include/asm/processor.h:55, > from include/linux/sched.h:13, > from kernel/ptrace.c:13: > In function 'fortify_memcpy_chk', > inlined from 'syscall_set_arguments.isra' at arch/riscv/include/asm/syscall.h:82:2: > include/linux/fortify-string.h:571:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] > 571 | __write_overflow_field(p_size_field, size); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > cc1: all warnings being treated as errors I certainly tested the series on riscv64, but somehow I haven't seen this compiler diagnostics before. > The compiler knows the size of the destination and the size to be copied > so it knows there will be an (intentional) overwrite here. > struct_group() would normally work but I think this structure already > has a struct_group() around some of the members that would be needed. I > build tested eliminating the memcpy() altogether, which would appear to > work, but I am not sure if there is a better solution, hence just the > report. > > Cheers, > Nathan > > diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h > index a5281cdf2b10..70ec19dc8506 100644 > --- a/arch/riscv/include/asm/syscall.h > +++ b/arch/riscv/include/asm/syscall.h > @@ -78,8 +78,11 @@ static inline void syscall_set_arguments(struct task_struct *task, > const unsigned long *args) > { > regs->orig_a0 = args[0]; > - args++; > - memcpy(®s->a1, args, 5 * sizeof(regs->a1)); > + regs->a1 = args[1]; > + regs->a2 = args[2]; > + regs->a3 = args[3]; > + regs->a4 = args[4]; > + regs->a5 = args[5]; > } I don't mind eliminating the memcpy() altogether, but I'd like to note that syscall_set_arguments() is an exact mirror of syscall_get_arguments(), so if the intentional overwrite in syscall_set_arguments() is not acceptable, then the intentional overread in syscall_get_arguments() shouldn't be acceptable either. -- ldv _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv