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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3D02C07545 for ; Tue, 24 Oct 2023 23:58:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344711AbjJXX64 (ORCPT ); Tue, 24 Oct 2023 19:58:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344663AbjJXX6x (ORCPT ); Tue, 24 Oct 2023 19:58:53 -0400 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 184C610CE for ; Tue, 24 Oct 2023 16:58:52 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id d2e1a72fcca58-6b26a3163acso4047563b3a.2 for ; Tue, 24 Oct 2023 16:58:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1698191931; x=1698796731; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=wXs6Pn0q7dHLwrvjv/VGOUkBCbTosuxQIWXIR0FEvR8=; b=BzzD391tHqE+Hh/rRCeKA7EZQdyRdcIn4BHeNGuTVkQKk08DUb5mxdxrKzkHv/a/4L 3LaLEdnSWG93YvE2yGrPXNy9IKB/ASVMIVyop33GDMXSzbvUd7SnEx2Chn9S5KrdrRs4 9Bqqs/WN0UVpUVupuPB0OiHqheYkFkveUT3FE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698191931; x=1698796731; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=wXs6Pn0q7dHLwrvjv/VGOUkBCbTosuxQIWXIR0FEvR8=; b=sPMFGq0nOlorgjJAAoiCPS+UJOFGFg36LVsGNq/ftAJkfNDnK2arpKFqrPtFBtPHMm lo4XWWU3wJ6kjIlRFHf1yw74nAzD9jFJaZSeuy+DKiTrPqkAvBFKJ3V7pKLNX+kw6GSI b/8hu/qU1HoNyQHkgIqsk6vjLeyAy6oh8DtaN3IAWzv42fEs2ObOpKBlktkx6BitZ4uB /TAV3AANmMs2WofIT0tjFKwI32lr6TSAEQXVHs0uT5YrQ5Y9FIdsmLGLbdpkbTEWBk6h J9iFn/+WN0aacTufvFV2WT+RJc45Q2URORzTmGgZYSxOBx0mJezZdwWZd6EInfS2ri4U wdyA== X-Gm-Message-State: AOJu0YxTQJkgP42yfKGH9fJwSSjPm9/sOXqTJc3S1gQ9j0Cv34SdMJn4 VWX5CqFTPSUMGXk5QwvDGsEpSA== X-Google-Smtp-Source: AGHT+IEBd9nH3qhCx7x7281KFVxT2YPG8yR28v8/pNE9HwnJxD7jTio62xVe2uyueP5+AwueOLYMoA== X-Received: by 2002:aa7:991e:0:b0:6b8:2ef3:331d with SMTP id z30-20020aa7991e000000b006b82ef3331dmr10232303pff.10.1698191931447; Tue, 24 Oct 2023 16:58:51 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id f11-20020aa79d8b000000b006b4a5569694sm8099281pfq.83.2023.10.24.16.58.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Oct 2023 16:58:50 -0700 (PDT) Date: Tue, 24 Oct 2023 16:58:50 -0700 From: Kees Cook To: Justin Stitt Cc: Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] s390/cio: replace deprecated strncpy with strscpy Message-ID: <202310241658.0144D73@keescook> References: <20231023-strncpy-drivers-s390-cio-chsc-c-v1-1-8b76a7b83260@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231023-strncpy-drivers-s390-cio-chsc-c-v1-1-8b76a7b83260@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Mon, Oct 23, 2023 at 07:24:38PM +0000, Justin Stitt wrote: > strncpy() is deprecated for use on NUL-terminated destination strings > [1] and as such we should prefer more robust and less ambiguous string > interfaces. > > We expect both `params` and `id` to be NUL-terminated based on their > usage with format strings: > > format_node_data(iuparams, iunodeid, &lir->incident_node); > format_node_data(auparams, aunodeid, &lir->attached_node); > > switch (lir->iq.class) { > case LIR_IQ_CLASS_DEGRADED: > pr_warn("Link degraded: RS=%02x RSID=%04x IC=%02x " > "IUPARAMS=%s IUNODEID=%s AUPARAMS=%s AUNODEID=%s\n", > sei_area->rs, sei_area->rsid, lir->ic, iuparams, > iunodeid, auparams, aunodeid); > > NUL-padding is not required as both `params` and `id` have been memset > to 0: > > memset(params, 0, PARAMS_LEN); > memset(id, 0, NODEID_LEN); > > Considering the above, a suitable replacement is `strscpy` [2] due to > the fact that it guarantees NUL-termination on the destination buffer > without unnecessarily NUL-padding. > > Note that there's no overread bugs in the current implementation as the > string literal "n/a" has a size much smaller than PARAMS_LEN or > NODEID_LEN. Nonetheless, let's favor strscpy(). > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@vger.kernel.org > Signed-off-by: Justin Stitt Looks good. Reviewed-by: Kees Cook -- Kees Cook