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 A7A77C433FE for ; Tue, 26 Apr 2022 16:48:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353263AbiDZQv1 (ORCPT ); Tue, 26 Apr 2022 12:51:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353258AbiDZQuS (ORCPT ); Tue, 26 Apr 2022 12:50:18 -0400 Received: from mail-ej1-x64a.google.com (mail-ej1-x64a.google.com [IPv6:2a00:1450:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9734747394 for ; Tue, 26 Apr 2022 09:45:39 -0700 (PDT) Received: by mail-ej1-x64a.google.com with SMTP id nd34-20020a17090762a200b006e0ef16745cso9335270ejc.20 for ; Tue, 26 Apr 2022 09:45:39 -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=bWOHkFAZUowQhXbgV/15IRTSfhe/pFIeo0hpg6VoqgU=; b=Y425LRYJ7pqp2qUV4Un5BKaPtlMc56oRipAYvk35bNiZHMqwQj5K1oHUY+3UtaBrm8 6F8LD23RH7puAqmN6VxxN3dzRPCX2o3jtXwChLes9m38UGHVO/PjltBdViFuvOO0/pv+ 9a5CV3vayhrQVrbmrEv1bjS0Nmz7caoEnvxuLCxERX2znPJk4SiPOZ9Qb7HS9LCHG3Lh qNuuAbPiqTn/Kfp6058UKfvV0NLpFCO10Egzm+8gacy2cKWG5HhTdR3sVdEPim8XyvUO oM/6bhYxYTS9e2sL18gV9sczR7Og8Y4lewCULG7qERx2rzD5bbV+C50LUjYRSUrnHoTG GPqg== 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=bWOHkFAZUowQhXbgV/15IRTSfhe/pFIeo0hpg6VoqgU=; b=hMvz0K0de9LvJSxo3fJ7YCr0OlS3zRvDvrXsuwdG94xxNHcgxEa7Pp7boAQRg9WnFK 0RfwHEjUvEcJbs2PLxuMJfdcrgltTeifv6d3TB9EQjSyP1Y3YyWuXREZMQA+ISnFMttJ ukAssNEyhZVwN5BiTzJTp+WQvg+sKxrg7lrU72P7l4TkLM1hy17y+VsobOaeS5DCg/Q5 T/jus6KPlBJGTZ7aFfPJFwIsDbBmqX+gglH04e6AJklezFrjK6zSWWeUALOGmayM1a8v dQjK+wNvHJ2WVjqyx0Ra1ikC8oVsA6hpVo1rReKbiHUq8P/OmXGUbkxFLigcoQf6VpxU 7f8g== X-Gm-Message-State: AOAM531SRc3RZEIQ6eU9tnklwuyipCBEGPkmdupiA3NduuvdoV4u/8zA slq1TsnSmQtabDjunfkhUKiN079XpmI= X-Google-Smtp-Source: ABdhPJy8hRX/dOnDKYiAzHg5kT/4VfAMjL04J1HrqWNmAu8buMPT+aF4N+PIwLqQH/MNoEjw6XwUMlGRDw4= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:d580:abeb:bf6d:5726]) (user=glider job=sendgmr) by 2002:aa7:c789:0:b0:413:605d:8d17 with SMTP id n9-20020aa7c789000000b00413605d8d17mr25370617eds.100.1650991538395; Tue, 26 Apr 2022 09:45:38 -0700 (PDT) Date: Tue, 26 Apr 2022 18:42:59 +0200 In-Reply-To: <20220426164315.625149-1-glider@google.com> Message-Id: <20220426164315.625149-31-glider@google.com> Mime-Version: 1.0 References: <20220426164315.625149-1-glider@google.com> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v3 30/46] kmsan: disable strscpy() optimization under KMSAN From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , 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 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org Disable the efficient 8-byte reading under KMSAN to avoid false positives. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/Iffd8336965e88fce915db2e6a9d6524422975f69 --- lib/string.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/lib/string.c b/lib/string.c index 485777c9da832..4ece4c7e7831b 100644 --- a/lib/string.c +++ b/lib/string.c @@ -197,6 +197,14 @@ ssize_t strscpy(char *dest, const char *src, size_t count) max = 0; #endif + /* + * read_word_at_a_time() below may read uninitialized bytes after the + * trailing zero and use them in comparisons. Disable this optimization + * under KMSAN to prevent false positive reports. + */ + if (IS_ENABLED(CONFIG_KMSAN)) + max = 0; + while (max >= sizeof(unsigned long)) { unsigned long c, data; -- 2.36.0.rc2.479.g8af0fa9b8e-goog