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 7B49BC433F5 for ; Tue, 29 Mar 2022 12:45:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236281AbiC2MrK (ORCPT ); Tue, 29 Mar 2022 08:47:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236597AbiC2MqG (ORCPT ); Tue, 29 Mar 2022 08:46:06 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23C0523F380 for ; Tue, 29 Mar 2022 05:41:57 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id z22-20020a50cd16000000b0041960ea8555so10962192edi.2 for ; Tue, 29 Mar 2022 05:41:56 -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=RDAmLqPngdYXKHnjNo9GDMAFOLr0Hdlw9RyMH9Gzg2s=; b=FNcO9gUSy3+PyH4e35W5RF6+lKn5SBE99oNAhVPz9pbYEq9m/C8L6ZgtW5ZmHXHd88 hQHJyPhLbOckmp0EqPMhP2HFzsxaGQxiGxliYPsshxLsXZvRvNDQ3UiI+w2rcId/Pty2 F64ZcwqpBt31uCBn0TdlaFTImU9JlBg1RYV2VHIqSgThEHMQahV/qTUZD+t5uPqd7ue6 fH/tn196F1PiJHLimD7A+gQDUww4aLBtiNt+XEamDrdfD269XRiydzui+vDM+yTJPgEp rF70JXIzeqHaym/T57YbYOQSbgbJ7VSdFIY7t07gue+zb/IWNfau8QfmJWCRW+7p6THF iMvw== 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=RDAmLqPngdYXKHnjNo9GDMAFOLr0Hdlw9RyMH9Gzg2s=; b=45hL1HBRzSO4jTPIfUpboyXSinmYPTy9cvT5vvzFRRTBlapSaQSTCBNu/swzExvbLs 2LpyP6MwApAmAbkItH6LsrqxF9vxvQAQkMx2/BrxGwpJEAXRqdXEjJ9gimG13NPr6bRm CwJWAfyTii7+kOWNa2VeOgmXNmnq5BxTk+R3EZbBteMp2Bi3WRkdkg9MM7Rs8XjzY4qu 4Wn7xvI0komk/B3OFQk1fFQQyp8XqIupG2ARs9YHyN5+HetyUTz10wCbYXfGgjF6vmP2 jnvr5E55OM6PCz1sstcx0G09j96Xk0zIV0Tsz3PrCozkcsUNETpMm1xtoS+jKvLsIuG7 qDFA== X-Gm-Message-State: AOAM531G9myZW01RhtvPZ8kzgRMZ3xPzChtTpP4b56cAZ6y5Naxzaec4 yjmGgXFLMBtyY2st3gQsmLB2L6smOPw= X-Google-Smtp-Source: ABdhPJzvRP1sTqhryqj6ueAWd65Bk5TF0Xd1dq7WPSkbBowXyk0DvSiadnoCaN6qak+2HIZ7cYi2Zk2fLDo= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:36eb:759:798f:98c3]) (user=glider job=sendgmr) by 2002:a17:906:af6b:b0:6df:83a9:67db with SMTP id os11-20020a170906af6b00b006df83a967dbmr34685899ejb.222.1648557715258; Tue, 29 Mar 2022 05:41:55 -0700 (PDT) Date: Tue, 29 Mar 2022 14:40:01 +0200 In-Reply-To: <20220329124017.737571-1-glider@google.com> Message-Id: <20220329124017.737571-33-glider@google.com> Mime-Version: 1.0 References: <20220329124017.737571-1-glider@google.com> X-Mailer: git-send-email 2.35.1.1021.g381101b075-goog Subject: [PATCH v2 32/48] 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 , 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-kernel@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; -- 2.35.1.1021.g381101b075-goog