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 3F333C433F5 for ; Fri, 24 Sep 2021 14:14:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D27BE610F7 for ; Fri, 24 Sep 2021 14:14:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D27BE610F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 651B9900004; Fri, 24 Sep 2021 10:14:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 600D8900002; Fri, 24 Sep 2021 10:14:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 517C2900004; Fri, 24 Sep 2021 10:14:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0218.hostedemail.com [216.40.44.218]) by kanga.kvack.org (Postfix) with ESMTP id 4542D900002 for ; Fri, 24 Sep 2021 10:14:08 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 0481E3208D for ; Fri, 24 Sep 2021 14:14:08 +0000 (UTC) X-FDA: 78622661376.11.5832391 Received: from mail-ot1-f46.google.com (mail-ot1-f46.google.com [209.85.210.46]) by imf09.hostedemail.com (Postfix) with ESMTP id B0B943000100 for ; Fri, 24 Sep 2021 14:14:07 +0000 (UTC) Received: by mail-ot1-f46.google.com with SMTP id 97-20020a9d006a000000b00545420bff9eso13271437ota.8 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=UDHLq13MQrTl98fTDLrI9RD1uSP0vBcd6SPfV5ujCXm8/9W0wmtmyYX6naISQQSmxP FErCSPpOUKQbwz0I4xOsDJrJTGzekJCZGWW1pAYLJ0mYzCNdjWSSu4cBhHQPYdhHh4V7 vDg0zNqe70BCsfrXjHQKJt5qw58LZAO8kthVtIn3WpwKMB9yPbTbOsqa2UxgZfzx3EYy m7Fk6fCFkhJJN32X2CbhLVSXVjDfcairU59bwvizh5vslWEhdyiiEJl0mxZbruWvi+38 fhbqkBhdx9qgbAShpwD4aj5ZTiO+TJPGG+fUjWVAOjL6pAI3hBtp7ihrdDscXQJaopZB 4Ocw== X-Gm-Message-State: AOAM531xYBvA3M1sqhoQazwcmszeN1+gdh8YfS5OO9hWpNDxN8MEqy0L yV6wzoUvdN3DPL/iEuZNAkYNVaI0DVVYGhcSGSR7/w== 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" X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: B0B943000100 X-Stat-Signature: q5x6y81fcscwp835654c34ywo3zn8jyr Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Xi0Xuiva; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf09.hostedemail.com: domain of elver@google.com designates 209.85.210.46 as permitted sender) smtp.mailfrom=elver@google.com X-HE-Tag: 1632492847-346766 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000027, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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