From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDA3184A40; Sat, 20 Jul 2024 16:42:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721493739; cv=none; b=sf6Zqos/mT+tDEmpq7Z8IUewgKLT6tcN71PsLeFEZQzaF62nxNkbJX/DyexPNPfwrwofjU7knvlcsoovkG0WTj0jSPyYjCmBLrP+XqE52P0L5bMMl3UoGNPDUuVzpHAofB/0pf50VfmEZWrjUasvnrPG9/52rbK6AazNNKRAWi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721493739; c=relaxed/simple; bh=IK1dKsFhTRKXjQWoSAzLI6OMePp8YPLTXexi7s1Fgxc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Mn6qGuQ9bRqeuyqxrtNmoPGKhmMJgfYFDEneJr0q/BF64K5IJw0mf/NrHhkhIpoGojj3TS1vXuP4QtgaBWYm6tiV28m8ERPePXgetwvB4DPL+VWwhMgUJjw8d6S8kKR6n45UdB2tln1V/OcujdrObv+ULvUms2GKeOKOHaRNGII= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Y5yVXHZS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Y5yVXHZS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34F1BC2BD10; Sat, 20 Jul 2024 16:42:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721493739; bh=IK1dKsFhTRKXjQWoSAzLI6OMePp8YPLTXexi7s1Fgxc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Y5yVXHZSmQNfq3QQF4eBe7LITL60eLZFX+p/wzTsSjB6NDMxGMi6VbOtFzUVBASS2 xLHiSjlfIczgqxwaZ3/x1p6y+AgERdpEr8/KOLdXiqws7yx65WKQP9d7D24qnbM+8c n1RZNxn9MX5NG8471N3S/8I1fSlXUIKUQnMtVUeTFkwdHfRvwU99nA6m9hMz+cbDdE 2N4dDAfMhfPC+eSoz07mxEKcPBnMl0tTKAaiE7R513Xu/7bf05NngiCGUHhDjGBTrN /EBEPhCQau4EFOdqQv6JrIe6HW18cbc/d4yJfvcTyXjRbl91P3oEZuqmvHqE5F+Unr Ssb4yoXDilX8g== Date: Sat, 20 Jul 2024 09:42:18 -0700 From: Kees Cook To: Jinjie Ruan Cc: chenhuacai@kernel.org, kernel@xen0n.name, gustavoars@kernel.org, arnd@arndb.de, maobibo@loongson.cn, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2] loongarch: Support RANDOMIZE_KSTACK_OFFSET Message-ID: <202407200940.ABE5F65@keescook> References: <20240719031427.119274-1-ruanjinjie@huawei.com> <202407190858.3097E9AF98@keescook> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sat, Jul 20, 2024 at 10:52:06AM +0800, Jinjie Ruan wrote: > > > On 2024/7/20 0:01, Kees Cook wrote: > > On Fri, Jul 19, 2024 at 11:14:27AM +0800, Jinjie Ruan wrote: > >> Add support of kernel stack offset randomization while handling syscall, > >> the offset is defaultly limited by KSTACK_OFFSET_MAX(). > >> > >> In order to avoid trigger stack canaries (due to __builtin_alloca) and > >> slowing down the entry path, use __no_stack_protector attribute to > >> disable stack protector for do_syscall() at function level. > >> > >> With this patch, the REPORT_STACK test show that: > >> `loongarch64 bits of stack entropy: 7` > > > > I suspect this will report the correct "6" after now that this commit > > has landed: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=872bb37f6829d4f7f3ed5afe2786add3d4384b4b > > Hi, Kees > > I noticed your patch, and I reconfirm that I have updated to the latest > mainline and that your patch is in the code. > > However，the following REPORT_STACK test of your below script has the > same result (run multiple times). > > And riscv64, arm64, x86 also has the 7 bit of stack entropy. Okay, thanks for checking! I may go take a closer look if I have time. It'd only be a problem if the distribution isn't sufficiently even. -Kees -- Kees Cook