From patchwork Tue Apr 26 16:42:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12827513 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9FF8C4332F for ; Tue, 26 Apr 2022 16:45:40 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 512516B0074; Tue, 26 Apr 2022 12:45:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 474D36B00A4; Tue, 26 Apr 2022 12:45:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 339FC6B00A5; Tue, 26 Apr 2022 12:45:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 20A556B00A3 for ; Tue, 26 Apr 2022 12:45:40 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 101BA60995 for ; Tue, 26 Apr 2022 16:45:40 +0000 (UTC) X-FDA: 79399606440.30.83CAB1B Received: from mail-ed1-f74.google.com (mail-ed1-f74.google.com [209.85.208.74]) by imf17.hostedemail.com (Postfix) with ESMTP id A82DD4004A for ; Tue, 26 Apr 2022 16:45:32 +0000 (UTC) Received: by mail-ed1-f74.google.com with SMTP id dk9-20020a0564021d8900b00425a9c3d40cso8110471edb.7 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=HD17Ebh8vePRfUfFISzG4L0U3msXHoimS7PpJ/tgq3bnEkG6X8qbbco+E6Xs4pTWCo p+kzFwF+UKB064YniJZL4llkiNX3spo2I1szCNZ/zeKhHVnVlfhkntPYpFDNMR6/hGDA NXLfkm3OtCEhYeDYNYfyXZY6uTYsOh9yrW6zf/kH5UcoUAD5xSW7KN5fm2xtBcRQWsUX PrEjEbqQ93lUaB+BzAMq2lABHAZg00j89G/8hOA9diBujuxvud9zC59axnUuvZf7MBwL Ap/0rJ8Mh1Z9dBr5/2bLNsMOZOzydk1fm+ouv/q/J1tlCQhnoCQW7n82UIRKxV69xoEf 8yTA== X-Gm-Message-State: AOAM5326P/AxDNVpwHWiLEbEG0tMlViUmUXIbfRNKwHUeDnVkrCX5spR HMZg7NCuq7KqlYjh1tGjBj9Xr8cRn2Y= 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 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A82DD4004A Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Y425LRYJ; spf=pass (imf17.hostedemail.com: domain of 3siFoYgYKCK8VaXSTgVddVaT.RdbaXcjm-bbZkPRZ.dgV@flex--glider.bounces.google.com designates 209.85.208.74 as permitted sender) smtp.mailfrom=3siFoYgYKCK8VaXSTgVddVaT.RdbaXcjm-bbZkPRZ.dgV@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Stat-Signature: epiwfwrijk7cumz8chxg7zf94yhkk7uc X-HE-Tag: 1650991532-485994 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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;