From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vmicros1.altlinux.org (vmicros1.altlinux.org [194.107.17.57]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 96BCC2505D2 for ; Tue, 8 Apr 2025 22:43:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.107.17.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744152218; cv=none; b=QD7OY68nfyErO4QX1ABp9dxvnyCuNTOlCCyNdq/UqcArgsIsrviO3j148olfk5THVh562t2245KbaUu1v2v2ArRRrgkwF1/5jo+8ZZULdMudLVT97s7Y18/NnSDD1VutRGh+MHtbJi/qTwBAF25JzKMPc/B4aFtuTZbwTfnuMek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744152218; c=relaxed/simple; bh=AmYdHqfVjCD657SNQEqPNHqdMzSO27jBYYDSCQbGIPA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jrSZTlct7k8gct4REB3kWe730Wv3YVrOixedQe+sGXb+JcgTlSs0bqzKTWWNEYJxv8V5QOwNNhttiYdEvOQ70JmPTr303p0F+9wmHK/1gKROJ4kSdUL0Pj6o+aiU/nTvBfzucZa/w63HceYXOWcIrQ1d/ytu6roMQ7Lva5d20yM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strace.io; spf=pass smtp.mailfrom=altlinux.org; arc=none smtp.client-ip=194.107.17.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strace.io Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=altlinux.org 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250408213131.GA2872426@ax162> 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