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 X-Spam-Level: X-Spam-Status: No, score=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F219C432C3 for ; Mon, 2 Dec 2019 15:51:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F32C320717 for ; Mon, 2 Dec 2019 15:51:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="EAekPwhr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F32C320717 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7B03E6B0003; Mon, 2 Dec 2019 10:51:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 787F36B0006; Mon, 2 Dec 2019 10:51:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 69C9A6B0007; Mon, 2 Dec 2019 10:51:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0095.hostedemail.com [216.40.44.95]) by kanga.kvack.org (Postfix) with ESMTP id 55F5E6B0003 for ; Mon, 2 Dec 2019 10:51:51 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id E344F181AEF10 for ; Mon, 2 Dec 2019 15:51:50 +0000 (UTC) X-FDA: 76220641980.16.lace25_84802c5bba018 X-HE-Tag: lace25_84802c5bba018 X-Filterd-Recvd-Size: 5818 Received: from mail-ua1-f68.google.com (mail-ua1-f68.google.com [209.85.222.68]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Mon, 2 Dec 2019 15:51:50 +0000 (UTC) Received: by mail-ua1-f68.google.com with SMTP id r13so33118uan.6 for ; Mon, 02 Dec 2019 07:51:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ZsHuwhZr/6ztwdd8q3CC0V3YSzcDYrsumwAiJt/X9Rs=; b=EAekPwhrw71m8Z4RdxADfM+lFYBlZN2hf0rvpakpSQzP9VZSaR1L3w2IQ/eivDiQ/p lduPHtP18tl/7SVqI1/v4hoTkjAIWHez+WWiwXxNGMLHVXsQFGIzqqTSsm1YrFr019BD Jb1TGLf0U+yC3j08KXA9ROO9TznEdHVhZobaQ3fwgtkDd60Y6WKXDHIgmVq0OYMNc9D/ VTXBSPRmIlst8eDc7q+DtpS9u36E4tuAZNLFwAQdTf20TBI012Bv7Q/A7XRMNiwTGQIA h5UuvXePAsj97STSegkaF0oF/n8whHE+TyrapCNNaTk0kECeLPE1roFjnQVSxgvKEeAV HrTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ZsHuwhZr/6ztwdd8q3CC0V3YSzcDYrsumwAiJt/X9Rs=; b=O0pZI3T5eFFhF0wAGivXoRGokpSzUOCe8lojBISOXxC/iJN5fvY5pPjgxI71u8HNvL DKWqUktQAszrfiYRMyz/NqbfidqxmUAJB0zjgEkwxTvdQZtEN9UVaWy/2whIfX2TB341 CzNRC5cCevLjN2fz0V4zHurd71TyBKKuILMFTN4FuW+C3FPMPG1GM5hM3xQ4nnorhdOv VnwC+R5NDsPBF/3f6bZRn7lBO865v2sO8KPUkGDWAxF/7CNpsrpe3RZTU+2xJYDLRCcp QIJmRLEdR65c1/tYNkdjz7Obcbj36jj6RMQ/amE4Gvz1QZwj/F/O+L26iSeLDhq9HkEQ Q/eQ== X-Gm-Message-State: APjAAAX2sRDg6sr2zqNHk0TLldAUjvVGEaUI/1jTRJ4Zz/2iKqiNq7Qi xW4vR+EArKEe6UB7PsCDXian6zlwuzqvZVZaTg9RMg== X-Google-Smtp-Source: APXvYqx3O5PJGKlU+cMfmxBBx/EXDN99g2aytBUa0bhZrE3lsCTKOpATIqvbQPZpSBa58PqhdPzsJtPq+TWQNx5wKpo= X-Received: by 2002:ab0:5512:: with SMTP id t18mr19323110uaa.128.1575301909099; Mon, 02 Dec 2019 07:51:49 -0800 (PST) MIME-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> <20191122112621.204798-32-glider@google.com> In-Reply-To: <20191122112621.204798-32-glider@google.com> From: Marco Elver Date: Mon, 2 Dec 2019 16:51:37 +0100 Message-ID: Subject: Re: [PATCH RFC v3 31/36] kmsan: disable strscpy() optimization under KMSAN To: Alexander Potapenko Cc: Vegard Nossum , Dmitry Vyukov , Linux Memory Management List , Al Viro , Andreas Dilger , Andrew Morton , Andrey Konovalov , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Christoph Hellwig , Christoph Hellwig , "Darrick J. Wong" , "David S. Miller" , Dmitry Torokhov , Eric Biggers , Eric Dumazet , Eric Van Hensbergen , Greg Kroah-Hartman , Harry Wentland , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jason Wang , Jens Axboe , Marek Szyprowski , Mark Rutland , "Martin K. Petersen" , Martin Schwidefsky , Matthew Wilcox , "Michael S. Tsirkin" , Michal Simek , Petr Mladek , Qian Cai , Randy Dunlap , Robin Murphy , Sergey Senozhatsky , Steven Rostedt , Takashi Iwai , "Theodore Ts'o" , Thomas Gleixner , Vasily Gorbik , Wolfram Sang Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 22 Nov 2019 at 12:28, wrote: > > Disable the efficient 8-byte reading under KMSAN to avoid false positives. > > Signed-off-by: Alexander Potapenko > To: Alexander Potapenko > Cc: Vegard Nossum > Cc: Dmitry Vyukov > Cc: linux-mm@kvack.org > > --- > > Change-Id: I25d1acf5c3df6eff85894cd94f5ddbe93308271c > --- > lib/string.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/lib/string.c b/lib/string.c > index 08ec58cc673b..15efdc51bda6 100644 > --- a/lib/string.c > +++ b/lib/string.c > @@ -186,7 +186,10 @@ ssize_t strscpy(char *dest, const char *src, size_t count) > if (count == 0 || WARN_ON_ONCE(count > INT_MAX)) > return -E2BIG; > > -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > +/** Why a doc comment? > + * Disable the efficient 8-byte reading under KMSAN to avoid false positives. > + */ AFAIK the CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS case is about unaligned accesses crossing page boundaries. In the #else case it's still going to do word-at-a-time if both src and dest are aligned, so the comment above is somewhat inaccurate. > +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && !defined(CONFIG_KMSAN) > /* > * If src is unaligned, don't cross a page boundary, > * since we don't know if the next page is mapped. > -- > 2.24.0.432.g9d3f5f5b63-goog >