From nobody Mon Apr 6 18:42:50 2026 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 F01C7C54EE9 for ; Mon, 5 Sep 2022 12:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238113AbiIEMcC (ORCPT ); Mon, 5 Sep 2022 08:32:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237881AbiIEMaX (ORCPT ); Mon, 5 Sep 2022 08:30:23 -0400 Received: from mail-wr1-x44a.google.com (mail-wr1-x44a.google.com [IPv6:2a00:1450:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DCDB606BF for ; Mon, 5 Sep 2022 05:26:33 -0700 (PDT) Received: by mail-wr1-x44a.google.com with SMTP id r23-20020adfb1d7000000b002286358a916so420632wra.3 for ; Mon, 05 Sep 2022 05:26:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date; bh=TqyxH/L5MkAtosS0jWqWllGGzUIesiLdVg3wG3p7XtY=; b=SRHbIOUb4DGUSlckCuBIb5D5nY2hugScbD5wJSkj9+gz5MDYNGyreOoUjr426hDozZ eIZwnOJAR9QbuL6MBljpr+ef5VyWMq7LE+MGIMu63m/ooGwVOtY9Wymo4x+ItRsbPuMF 3x3WktXqUtSalOy5ST4UA3C+QVvz/PUjD2mQzbD9n6SlVfmNFgRe+dRr3wA+uShralze F5IELO9fjYSA2cgSGi/7JeC9JLPRXPbVVnHX/AfgjNsTAchbmP+32JYRVNVmU8xLiZ/2 5IjHNbRGxFz5C2uzmzWFN1Wc7yPI/jBEojh1hnBnCwk9zy4n2ozIysDaR+/OsHRccZvb k9Lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=TqyxH/L5MkAtosS0jWqWllGGzUIesiLdVg3wG3p7XtY=; b=RkURWVLdnicbi4MZhOG5l/15gRvAwlcMppJywGuYvkAdfZTcDDcV4/fOfYDJXPJ6IS 9jBLsjbr6cc8qWMc4xNOujGFpgJi7I3kjnIdZF+oqpIFjDYXKU41QEapLqbQ3zMIosbw Ury/b6H88NKHeYslWkYwZv4iuvNzZ3o/ikzgKiKQozCRDX97L3sz8FOkTy3S5llxQs6Q fgk6Xijy33+Tqyh+H35hHr+6L49uxSrINfhD6MEz0/4bi1jvmPzaCvI8ilH/jVeGkuHL slfCN24JsOgpxiaJW8kGLmzSTUp6f+DTncaLx73e4s+37UAPZdtefRA9wTacSqojOdJO tLpQ== X-Gm-Message-State: ACgBeo1FOF5FBkRfW852MfXErilG875mPCH41AgxHKIXKEK4amTmicSD lWaWAjh6J9t+8tNTtxzrK7tu934WmMc= X-Google-Smtp-Source: AA6agR7gpIA9Ys+R+97x8E6SItr56wFcMnWLG4Y2aVvt4HKxaJejCTap6PHw9s2SK+DWSs3ZsGMtcLcy1oM= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:b808:8d07:ab4a:554c]) (user=glider job=sendgmr) by 2002:a5d:584b:0:b0:220:7624:5aae with SMTP id i11-20020a5d584b000000b0022076245aaemr24101908wrf.119.1662380780114; Mon, 05 Sep 2022 05:26:20 -0700 (PDT) Date: Mon, 5 Sep 2022 14:24:38 +0200 In-Reply-To: <20220905122452.2258262-1-glider@google.com> Mime-Version: 1.0 References: <20220905122452.2258262-1-glider@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220905122452.2258262-31-glider@google.com> Subject: [PATCH v6 30/44] kcov: kmsan: unpoison area->list in kcov_remote_area_put() 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" KMSAN does not instrument kernel/kcov.c for performance reasons (with CONFIG_KCOV=3Dy 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 --- v4: -- change sizeof(type) to sizeof(*ptr) -- swap kcov: and kmsan: in the subject Link: https://linux-review.googlesource.com/id/Ie17f2ee47a7af58f5cdf716d585= ebf0769348a5a --- kernel/kcov.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kcov.c b/kernel/kcov.c index e19c84b02452e..e5cd09fd8a050 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_ar= ea *area, INIT_LIST_HEAD(&area->list); area->size =3D 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(area->list)); } =20 static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct tas= k_struct *t) --=20 2.37.2.789.g6183377224-goog