From nobody Tue Apr 7 16:31:00 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 AC8C9ECAAA3 for ; Fri, 26 Aug 2022 15:16:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344190AbiHZPQY (ORCPT ); Fri, 26 Aug 2022 11:16:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244354AbiHZPOn (ORCPT ); Fri, 26 Aug 2022 11:14:43 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9B941839F for ; Fri, 26 Aug 2022 08:10:05 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-33daeaa6b8eso29549037b3.7 for ; Fri, 26 Aug 2022 08:10:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc; bh=4pDNTP8Rcz1c/6m0qOjb0X1O42ovrN3YaDrJNkQcLng=; b=D8g9K+F2VtTbVGCiyA3gHOZ8vWyfLv3kiBVO8NzVmbbuaiAQz5lidowjJcTUnqN9NV 0M45L50FmJ4PxOKToUEzR27CpoNoU/oyH1Qxm5OUEXk0XU/8/XXprRa1vk5Bi3TeJfkw q081N/bHUsn7mQv/yoQ1Ey2nzz9m+S9Fo7PM6zBWmqx38XFTQk025tvKxOEGgVZjqGty /9F1JErkTDPulPdl0zxIDtlkVyQUOPBuGPdH9gBMfPQwL19d8No0nlzWwOQohCYKDZm6 MPulEwsqymX7KjroU/sIuuObTC/BUFlxcZTS2qy9QDHhU8TveQCUg6HprGxaMBW2ev2v GJow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc; bh=4pDNTP8Rcz1c/6m0qOjb0X1O42ovrN3YaDrJNkQcLng=; b=hHZfaBIsk+MHOVjKbrrCD6WuRZNZRDj8MOXqKQ3LIHwJ1P1tzjuJ9Ad2YZnyctaZjh tTPLMArEtQ6kaezmCqcFDJs3zZpW2QeXAtu4U0J9zUQDs5mgFZ60t1vB2G8nbKT51gHQ UElhzOHc0oaxZI9kWivZiD4iU1cfxbUAZWadFaP3EKZV68mVlnSH5pCjS1gfcd0LEXic +JMIogjLFTSdrCgMenn1tG5cHsX20xZwRHflRx24QdS3Qb6rtuAlkb0qOu2k+qaKsnh/ sWeIkdcof2fbjunt9HPuvonG5ymvplReaBaxRofPq2tL5e9PMZsemV0h0pixzdPik9vt oXgA== X-Gm-Message-State: ACgBeo1O4Hfexi3lLmoR4anP14QsROhLaWmj0S//zqkyh/XcQInw5R/t XQ3jUfz4rJPu/feVRYOvobcr3vr7zaM= X-Google-Smtp-Source: AA6agR5vVQmtlhIgTKQ7dnFjHT2Qul1eY6YRiLp6VijdR+cm0ab1oQKWZ6dDBOhtA58d0ZDce6nTKPF8G7g= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:5207:ac36:fdd3:502d]) (user=glider job=sendgmr) by 2002:a05:6902:10ca:b0:671:3616:9147 with SMTP id w10-20020a05690210ca00b0067136169147mr92484ybu.105.1661526602616; Fri, 26 Aug 2022 08:10:02 -0700 (PDT) Date: Fri, 26 Aug 2022 17:08:02 +0200 In-Reply-To: <20220826150807.723137-1-glider@google.com> Mime-Version: 1.0 References: <20220826150807.723137-1-glider@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220826150807.723137-40-glider@google.com> Subject: [PATCH v5 39/44] 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 33f4d4baba079..697da8dae1418 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -128,7 +128,9 @@ 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 2.37.2.672.g94769d06f0-goog