From nobody Sun Feb 8 09:03:13 2026 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 52F05C433EF for ; Fri, 1 Jul 2022 14:29:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233044AbiGAO3w (ORCPT ); Fri, 1 Jul 2022 10:29:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232736AbiGAO26 (ORCPT ); Fri, 1 Jul 2022 10:28:58 -0400 Received: from mail-lj1-x249.google.com (mail-lj1-x249.google.com [IPv6:2a00:1450:4864:20::249]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 166AB3D491 for ; Fri, 1 Jul 2022 07:25:14 -0700 (PDT) Received: by mail-lj1-x249.google.com with SMTP id m8-20020a2eb6c8000000b0025aa0530107so505280ljo.6 for ; Fri, 01 Jul 2022 07:25:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=MLo3LhenoRrRqNTI2r4mtWD3J0vGsm9bvjleadBpMkY=; b=anOUkKWtulGEKBkArfZgJyNh0cGJx9d7Cq23k1uQwOBaeBk8BsWD249jvt+waaUJ0W wFq6nFfeaRMqhTZBfdHnekYcU9Y6DlOKwhd7zz8Pwv5Mf7POcnXxXlRO9IdWwc7sHxG8 EJehSvYRYGgoI66twoBlGoYEACzjwkAkNmneLnfsKkPQFvcZRfWhgQAodIu6D09PjFk8 Icdf6H3+rBIz7HcFSJ3Z9tX02BV8EOgwwt+6yOVuoCYfJOPeNjzAXzZ5xayTIEyTNe+u 12rzA9yQKhB/zdr6mRJsJWTzWXROIdNbnWlGX7VZEuLugd3XmFTzxEYhZNDwatZ7SBn9 IL1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=MLo3LhenoRrRqNTI2r4mtWD3J0vGsm9bvjleadBpMkY=; b=WNSywBmoRmo5fsmKUj1TyulV9WPuSawcZ1B2By+KahxQ2AhAdeJmDTDzAe+O3w5OK2 cCBJPSsmdOUQRVuSCqWWemYzCXcK9BgE5vd1G1/3Sq4bt5esTyd00badIk8Q6eSAV+Iu ifFbB/lENO6HTzoOFqdxckrJHL2MQMDB7aMrpvzM2NX++gw4ITMopPOyBxewXQ7Tc29g 8v+a3YZaL72zDVRifBkcUbOc5RdlTo7nqbBKxflPfju2GIiVarxalJklyjVG7WO+kKHv St0zaXBDbO7c9mXEvsmiPTowf0H5fUhiWXyGurJ2VODG57bHMwXAwOi3Cf8oHQJYCjfP kglg== X-Gm-Message-State: AJIora/prU25NfDk69eYBSl8n4K9BEI/fpfH/o5YziwHfz0w2KVavm8+ Ok77Om3wmfiE1foDg7PeLzcPGgDmBn0= X-Google-Smtp-Source: AGRyM1vhkmL+KohFz0MszVF5zMXVYF2SuHbeJwCxM549Y5UN3wtICSWeskVNj4IhdECyposUmY2NkdReg2A= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:a6f5:f713:759c:abb6]) (user=glider job=sendgmr) by 2002:a05:6512:e83:b0:47f:635c:3369 with SMTP id bi3-20020a0565120e8300b0047f635c3369mr8918326lfb.659.1656685504982; Fri, 01 Jul 2022 07:25:04 -0700 (PDT) Date: Fri, 1 Jul 2022 16:23:04 +0200 In-Reply-To: <20220701142310.2188015-1-glider@google.com> Message-Id: <20220701142310.2188015-40-glider@google.com> Mime-Version: 1.0 References: <20220701142310.2188015-1-glider@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v4 39/45] x86: fs: kmsan: disable CONFIG_DCACHE_WORD_ACCESS From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Andrey Konovalov Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" dentry_string_cmp() calls read_word_at_a_time(), which might read uninitialized bytes to optimize string comparisons. Disabling CONFIG_DCACHE_WORD_ACCESS should prohibit this optimization, as well as (probably) similar ones. Suggested-by: Andrey Konovalov Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/I4c0073224ac2897cafb8c037362= c49dda9cfa133 --- arch/x86/Kconfig | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4a5d0a0f54dea..aadbb16a59f01 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -129,7 +129,9 @@ config X86 select CLKEVT_I8253 select CLOCKSOURCE_VALIDATE_LAST_CYCLE select CLOCKSOURCE_WATCHDOG - select DCACHE_WORD_ACCESS + # Word-size accesses may read uninitialized data past the trailing \0 + # in strings and cause false KMSAN reports. + select DCACHE_WORD_ACCESS if !KMSAN select DYNAMIC_SIGFRAME select EDAC_ATOMIC_SCRUB select EDAC_SUPPORT --=20 2.37.0.rc0.161.g10f37bed90-goog