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 08FE0C433FE for ; Tue, 29 Mar 2022 12:47:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232964AbiC2Mtg (ORCPT ); Tue, 29 Mar 2022 08:49:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235979AbiC2MrK (ORCPT ); Tue, 29 Mar 2022 08:47:10 -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 095CF2571A3 for ; Tue, 29 Mar 2022 05:42:07 -0700 (PDT) Received: by mail-ej1-x64a.google.com with SMTP id ml20-20020a170906cc1400b006df8c9357efso8111804ejb.21 for ; Tue, 29 Mar 2022 05:42:07 -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=XAH4acQx+nIWehlAydXzel6kNYbNIXLv2CmwLsxzisk=; b=YpPQVEPURN2ajRY1n46PwqwFtWp7RlcVqb0MoMfwIeS/m0CwFkAlmK9veRToXX/Nh0 b6E4uZScKbMj2h/RFOMhq1XJYUrJq4RW8RMzRp9Z6yBNz7KYsvHe+FzobtEv1SE+z8z0 bBRHxkEnq08sMogy1ImUi3Oswt0oie9fh2FqU81kZAPoJIolXyiL4DuviryqlAYyJ0cl fP2//D93tGjpn2gvBqCfUGSh263yJnEsQm+Ik3DPQuyteuBuA1cheprPsGBkm0p9BeA1 Z+owbpU+GHDWSgeR7eKuS6SEv9VgACxZntokNlAC2HOBzVv0eGiDKuMeIWei48sQH+i1 OfdQ== 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=XAH4acQx+nIWehlAydXzel6kNYbNIXLv2CmwLsxzisk=; b=LIl+Na2Jcw8UL0Yk/o7rsbI/slBTO6vv+xky15IHxIHu2PqEJi9DEA0ZgLEnAw9Ntd /R1J/0tB+itlkr/Neqjdd/RXfrrRiEAsTXmX4zGPAmOSPpcYUa7/y/JqdxGQldGc+PX0 92ZJWNCHcjDiT9DF0tR9n+cHpUOCo4Fx/+XvpB+dgaD8Fw3V/B2emGO3nJFUND14it/W j1HKpt4eVdpDHLWrlSYgCRe7+73QE63n9tJDWDuVB9wHQqdnR0esC/ZoNaRPk2XXx73M hjC3NpvvJCHu2zfJVwN+xnBkI5SB4Vx3w7Gk/Xu8UR7rw/Iyyn2j+Ud6N0dDg8xUc6/m GZEA== X-Gm-Message-State: AOAM531xy9sznroCs7COV7BUj75hTYM0h0Lx07G/V6yD2bl25rXlyu1L mL8+CTQqtep4Zdh5y1hZJsvWUSN+VHs= X-Google-Smtp-Source: ABdhPJw8wyFM62Ut2Sf7rG+vUT6fWVoAt6oG05coCAtugWeflqaBDOLOCgDn81VaIvvOcjBAOP8lwoc0QHY= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:36eb:759:798f:98c3]) (user=glider job=sendgmr) by 2002:a17:906:4313:b0:6b8:b3e5:a46 with SMTP id j19-20020a170906431300b006b8b3e50a46mr33446870ejm.417.1648557725791; Tue, 29 Mar 2022 05:42:05 -0700 (PDT) Date: Tue, 29 Mar 2022 14:40:05 +0200 In-Reply-To: <20220329124017.737571-1-glider@google.com> Message-Id: <20220329124017.737571-37-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 36/48] kmsan: kcov: unpoison area->list in kcov_remote_area_put() 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-arch@vger.kernel.org KMSAN does not instrument kernel/kcov.c for performance reasons (with CONFIG_KCOV=y virtually every place in the kernel invokes kcov instrumentation). Therefore the tool may miss writes from kcov.c that initialize memory. When CONFIG_DEBUG_LIST is enabled, list pointers from kernel/kcov.c are passed to instrumented helpers in lib/list_debug.c, resulting in false positives. To work around these reports, we unpoison the contents of area->list after initializing it. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/Ie17f2ee47a7af58f5cdf716d585ebf0769348a5a --- kernel/kcov.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kcov.c b/kernel/kcov.c index 36ca640c4f8e7..88ffdddc99ba1 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -152,6 +153,12 @@ static void kcov_remote_area_put(struct kcov_remote_area *area, INIT_LIST_HEAD(&area->list); area->size = size; list_add(&area->list, &kcov_remote_areas); + /* + * KMSAN doesn't instrument this file, so it may not know area->list + * is initialized. Unpoison it explicitly to avoid reports in + * kcov_remote_area_get(). + */ + kmsan_unpoison_memory(&area->list, sizeof(struct list_head)); } static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t) -- 2.35.1.1021.g381101b075-goog