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 X-Spam-Level: X-Spam-Status: No, score=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A96A4C433FE for ; Fri, 24 Sep 2021 14:14:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84B8C61164 for ; Fri, 24 Sep 2021 14:14:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346008AbhIXOPl (ORCPT ); Fri, 24 Sep 2021 10:15:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231683AbhIXOPk (ORCPT ); Fri, 24 Sep 2021 10:15:40 -0400 Received: from mail-ot1-x334.google.com (mail-ot1-x334.google.com [IPv6:2607:f8b0:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90C19C061571 for ; Fri, 24 Sep 2021 07:14:07 -0700 (PDT) Received: by mail-ot1-x334.google.com with SMTP id r43-20020a05683044ab00b0054716b40005so6419150otv.4 for ; Fri, 24 Sep 2021 07:14:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=8K4PrtN7OiONQx5lRLM4t8rDUMaxWp8v0q/xipOZJhQ=; b=Xi0XuivaEIrO+GSXqPZiG2AVUrhMgxq5Xd2mrvhBXmLL1K2Ra8+1Pj5uVCYrWJPl5a J6103kv3+tewtdVyIFABqogT3WJU0zD/45S6WSn5WSyxh+AnN4piAT7OJDzLiPH72RYr bHG6C9MVWldKDhuSag4yWOY7+bYlZA2w+BrBEvAu1FzM0brOsDdPi4oVv7tA+QlhSCam DS2z2oyuqmJwA3KPnuObgokqdzssdMVZnP2S7Y3L2zCjzojwH1TuQZgjYLzwY6opkaJZ 4VWbWC2AdvyLPGg/DYo+8hfeOye7cXbZijjh+xHTrYiCqa0qeewghb+hk+fhwJhFhyyO UT4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=8K4PrtN7OiONQx5lRLM4t8rDUMaxWp8v0q/xipOZJhQ=; b=ag308PsfH5/QUaOoPB1j8MwTw1qb1kf6fDdCnmlNNxyGHRkS+5pbLgngpCj3pt5/pb sPZJ/rcsE0VBsnNwiG1FnUJ7stANJhI0mgOWxCObKgwap6G6Wu/khE1pDLP9hN7YsyHR 6o789JQEhY9gQjmuCmjm6UwXGyWkGqgwmGProTpYuhlxgaco7QgeT0hSqd5S+k4N/x2m kHVkrulwovhZHfo4ChXAWsRvm2Qk4WOLOpjaj1IQdHZpIqd1ILJnoic98kW4XxsJaS9o 8prwZU5eYDrz1wLisfqpsWzpJ+CbyKyZlGBUTlAEiu4FXZyPeR8dkU2xuvYBQerZshUN 25zg== X-Gm-Message-State: AOAM530qFlX24TAQr6X63qMSLjQ4rQoqyQmRBe0oA4SUuSn2TdEmc03m F1UfxC+Q5kllPmYMLhUCYJSsXjIWpqF14HefMjvsSQ== X-Google-Smtp-Source: ABdhPJwbJUHVLc9n11N5tQ+Sx1J70AO6/auS7KX7WvVSqARGdj7zxIcuHgPjpLy7waUrdkpGiU1JBpADebK25fFigLo= X-Received: by 2002:a05:6830:791:: with SMTP id w17mr4311950ots.108.1632492846701; Fri, 24 Sep 2021 07:14:06 -0700 (PDT) MIME-Version: 1.0 References: <1632485642-20625-1-git-send-email-manjeet.p@samsung.com> In-Reply-To: <1632485642-20625-1-git-send-email-manjeet.p@samsung.com> From: Marco Elver Date: Fri, 24 Sep 2021 16:13:55 +0200 Message-ID: Subject: Re: [PATCH] mm/kfence: Null check is added for return value of addr_to_metadata To: Manjeet Pawar Cc: glider@google.com, dvyukov@google.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, r.thapliyal@samsung.com, a.sahrawat@samsung.com, v.narang@samsung.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 24 Sept 2021 at 15:55, Manjeet Pawar wrote: > This patch add null check for return value of addr_to_metadata(). > currently 'meta' is geting accessed without any NULL check but it is > usually checked for this function. > > Signed-off-by: Manjeet Pawar Your commit message does not make sense -- what bug did you encounter? "usually checked for this function" is not a reason to add the check. Adding a check like this could also hide genuine bugs, as meta should never be NULL in __kfence_free(). If it is, we'd like to see a crash. Did you read kfence_free() in include/linux/kfence.h? It already prevents __kfence_free() being called with a non-KFENCE address. Without a more thorough explanation, Nack. Thanks, -- Marco