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 6416CCDB47E for ; Wed, 18 Oct 2023 23:33:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231991AbjJRXdf (ORCPT ); Wed, 18 Oct 2023 19:33:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229679AbjJRXdd (ORCPT ); Wed, 18 Oct 2023 19:33:33 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34E16B6; Wed, 18 Oct 2023 16:33:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697672012; x=1729208012; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=mufGButwLpL6uBFFn43+xl6wMGqTQF8VWI+npPtC0G4=; b=AgEgG8UTP4ndxlQOZsDuoVvzMlbAg70DlpfM2vTnaY/bNsOVz5cnNYDN HjscOcAzfWwy9rGWZ+8PxKMTh5V2r1kuuha3cjycVOCc3Y24jE6aen5bC Os10UuJwCFues+DSiVsvocHI5jrsb3hi9ZUUUw2huO63fp3zhXdFNJq1z bzYZoHxtHVT9kO7dmWrkND5QTVLs/dH/VlyK/BV7yfwwlk3t11IsHi8DH BOzzKkE+z2Q2QWJSGAo8FNC7q+97CuIqm2UFICwlk2RwrFD9K79nq+WyT bP9RZXhlbL7Xza1ZOtOkQA8TIqQdtQ8GpBnYJBBsKcGxfkZ6h3XPa/TN9 A==; X-IronPort-AV: E=McAfee;i="6600,9927,10867"; a="366380843" X-IronPort-AV: E=Sophos;i="6.03,236,1694761200"; d="scan'208";a="366380843" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2023 16:33:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10867"; a="750293083" X-IronPort-AV: E=Sophos;i="6.03,236,1694761200"; d="scan'208";a="750293083" Received: from aschofie-mobl2.amr.corp.intel.com (HELO aschofie-mobl2) ([10.212.171.196]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Oct 2023 16:33:31 -0700 Date: Wed, 18 Oct 2023 16:33:29 -0700 From: Alison Schofield To: Justin Stitt Cc: Dan Williams , Vishal Verma , Dave Jiang , Ira Weiny , nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] block: replace deprecated strncpy with strscpy Message-ID: References: <20231018-strncpy-drivers-nvdimm-btt-c-v1-1-58070f7dc5c9@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 18, 2023 at 03:39:59PM -0700, Justin Stitt wrote: > I have a feeling I may have botched the subject line for this patch. > Can anyone confirm if it's good or not? > > Automated tooling told me that this was the most common patch > prefix but it may be caused by large patch series that just > happened to touch this file once. > > Should the subject be: nvdimm/btt: ... ? > > Judging from [1] I see a few "block" and a few of nvdimm/btt. Hi Justin, It should be nvdimm/btt because it only touches btt.c. Here's the old school way that I use to find prefixes. Maybe you can train your automated tooling to do this, and then share it with me ;) I do: ~/git/linux/drivers/nvdimm$ git log --pretty=oneline --abbrev-commit btt.c 3222d8c2a7f8 block: remove ->rw_page ba229aa8f249 nvdimm-btt: Use the enum req_op type 86947df3a923 block: Change the type of the last .rw_page() argument 8b9ab6266204 block: remove blk_cleanup_disk 3205190655ea nvdimm-btt: use bvec_kmap_local in btt_rw_integrity 322cbb50de71 block: remove genhd.h And I see a few choices, with 'block' being pretty common. I peek in those patches and see that block was used when the patch included files in drivers/block AND also in nvdimm/btt. Use nvdimm/btt for your patch. A bit more below - > > On Wed, Oct 18, 2023 at 3:35 PM 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 super->signature to be NUL-terminated based on its usage with > > memcpy against a NUL-term'd buffer: > > btt_devs.c: > > 253 | if (memcmp(super->signature, BTT_SIG, BTT_SIG_LEN) != 0) > > btt.h: > > 13 | #define BTT_SIG "BTT_ARENA_INFO\0" > > > > NUL-padding is not required as `super` is already zero-allocated: > > btt.c: > > 985 | super = kzalloc(sizeof(struct btt_sb), GFP_NOIO); > > ... rendering any additional NUL-padding superfluous. > > > > 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. > > > > Let's also use the more idiomatic strscpy usage of (dest, src, > > sizeof(dest)) instead of (dest, src, XYZ_LEN) for buffers that the > > compiler can determine the size of. This more tightly correlates the > > destination buffer to the amount of bytes copied. > > > > Side note, this pattern of memcmp() on two NUL-terminated strings should > > really be changed to just a strncmp(), if i'm not mistaken? I see > > multiple instances of this pattern in this system. I'm not following this note about memcmp() usage. Where is that? > > > > 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 > > --- > > Note: build-tested only. > > > > Found with: $ rg "strncpy\(" How you found it goes in the commit log, not below the line. > > --- > > drivers/nvdimm/btt.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c > > index d5593b0dc700..9372c36e8f76 100644 > > --- a/drivers/nvdimm/btt.c > > +++ b/drivers/nvdimm/btt.c > > @@ -986,7 +986,7 @@ static int btt_arena_write_layout(struct arena_info *arena) > > if (!super) > > return -ENOMEM; > > > > - strncpy(super->signature, BTT_SIG, BTT_SIG_LEN); > > + strscpy(super->signature, BTT_SIG, sizeof(super->signature)); > > export_uuid(super->uuid, nd_btt->uuid); > > export_uuid(super->parent_uuid, parent_uuid); > > super->flags = cpu_to_le32(arena->flags); > > > > --- > > base-commit: 58720809f52779dc0f08e53e54b014209d13eebb > > change-id: 20231018-strncpy-drivers-nvdimm-btt-c-15f93879989e > > > > Best regards, > > -- > > Justin Stitt > > > > [1]: https://lore.kernel.org/all/?q=dfn%3Adrivers%2Fnvdimm%2Fbtt.c > > Thanks > Justin >