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 9DA3FC43334 for ; Fri, 1 Jul 2022 14:27:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232180AbiGAO1W (ORCPT ); Fri, 1 Jul 2022 10:27:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232080AbiGAO0b (ORCPT ); Fri, 1 Jul 2022 10:26:31 -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 950864F1B6 for ; Fri, 1 Jul 2022 07:24:29 -0700 (PDT) Received: by mail-ej1-x64a.google.com with SMTP id hs18-20020a1709073e9200b0072a3e7eb0beso843661ejc.10 for ; Fri, 01 Jul 2022 07:24:29 -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=BanD6+8XMfAM/imhDA9kzvs2Y65ZtmV55Antiu9BWiI=; b=mRTIF6L84JAlg2BdRm6GzX0JAROwRk/sEAnHEyfcCrrVzpgYQDP4s07FuADnqgr6wB ksMNaoreBTcwNzLVqW2CLQ5LB7q3aAIulZLYB9nuQCnWIkiiRq/Q6VQMDSS0zlOVULIz Ix5FQ2wgYo7L210aM/fKxFuU2tFPKcIZsO4Bd7Rml1N7o3/Qm7KUm5NB65g2Iem/FeNl 60bw+n3Gge8W8wvYFmfBqE0m7x4Rd1oXGrEp9Fu06BG/VFY3yN6zDkc7HdcrNddl9RFZ bKRR73XyhRvmnmBNBCirP4336bKCGzJJU7II1NZsV//Tb+lcEnJtFA9n/GAdR4WOxrCR uhTA== 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=BanD6+8XMfAM/imhDA9kzvs2Y65ZtmV55Antiu9BWiI=; b=SrhzZPHWFNq6ciSQW0wycsnwk9DIBrKi3VXPI1XEUWSfWX5RY23jWT9eTrDhEWmJvi mFGs9bYT4sK+OL5N8vpH5FPZ1dbomX8GFL2mUTdhQ8XD0xDIR17d231rgBGpkMmwKccp e1jF0gVJcbjt6J+8EkihSdY+Fj0dGtjO0DpGFc9rhJm+VZd6aIrcQ5BRQuYRRVqhIu55 QJVEw7InBlkEMHxGTBjqstRVPoQOdY4+vfkP+aJyD7A5y0yUTDBwqEjIRrbufD2uCh7y sojgugP3QeIxLXk4BQyFE6KY5IkmabbEptpTtnCRBtEL3tWaYPZWKkbDKpGx1wzX+/Dx sB2A== X-Gm-Message-State: AJIora+i4KWyLYlCos1+GXf1vKwLLex/zcIfPKjeT/e3dVdX4g3OkhFq cnB8A2xcENeInRlz6ORBU3ogITpjmek= X-Google-Smtp-Source: AGRyM1siOEbFYB7M2t/Uxp+hgW7r6Fq8QtqzrawcUEK1N9TlhUHD1diimHPgmIHCv/uA9yMN9zjsG0VRP+I= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:a6f5:f713:759c:abb6]) (user=glider job=sendgmr) by 2002:a50:fe0c:0:b0:435:510a:9f1f with SMTP id f12-20020a50fe0c000000b00435510a9f1fmr19625057edt.297.1656685468052; Fri, 01 Jul 2022 07:24:28 -0700 (PDT) Date: Fri, 1 Jul 2022 16:22:51 +0200 In-Reply-To: <20220701142310.2188015-1-glider@google.com> Message-Id: <20220701142310.2188015-27-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 26/45] kmsan: disable strscpy() optimization under KMSAN 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 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 6f334420f6871..3371d26a0e390 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; -- 2.37.0.rc0.161.g10f37bed90-goog