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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 E8CF5C433DB for ; Wed, 27 Jan 2021 12:17:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5E3C620786 for ; Wed, 27 Jan 2021 12:17:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5E3C620786 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E09C66B0008; Wed, 27 Jan 2021 07:17:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DBA3F6B000A; Wed, 27 Jan 2021 07:17:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CF60F6B000C; Wed, 27 Jan 2021 07:17:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0055.hostedemail.com [216.40.44.55]) by kanga.kvack.org (Postfix) with ESMTP id BA6766B0008 for ; Wed, 27 Jan 2021 07:17:13 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 7BD6D1EF1 for ; Wed, 27 Jan 2021 12:17:13 +0000 (UTC) X-FDA: 77751454746.27.bear00_0c0b92b27596 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id 603CC3D663 for ; Wed, 27 Jan 2021 12:17:13 +0000 (UTC) X-HE-Tag: bear00_0c0b92b27596 X-Filterd-Recvd-Size: 2606 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Wed, 27 Jan 2021 12:17:12 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611749831; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZWGhIGpq32r8yQhFCh/u7TJyjEdLNEe21nUOsEEzA0s=; b=BifLfo5TLwia3n6VCUvaSJbUCuF5sGHvSecgKF2YvHEJmt0FlKh3tGFnxzlxQyQxg13zRJ 32DSJcEZLBZ1CAZ6gRc3j8sFoa3y8wmxC6zE+V0eUJpbcPY3M7GeOZYAVSAMf6FO+0YJuY Jy2kZX+R2m1ppQrfP8ijAQMeqc2TD7A= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BD8C3AC9B; Wed, 27 Jan 2021 12:17:11 +0000 (UTC) Date: Wed, 27 Jan 2021 13:17:11 +0100 From: Michal Hocko To: Tetsuo Handa Cc: Andrew Morton , linux-mm@kvack.org, Sabyrzhan Tasbolatov Subject: Re: [PATCH v3] mm: memdup_user*() should use same gfp flags Message-ID: References: <20210126111315.858994-1-snovitoll@gmail.com> <20210127105538.4919-1-penguin-kernel@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: On Wed 27-01-21 12:59:28, Michal Hocko wrote: > On Wed 27-01-21 19:55:38, Tetsuo Handa wrote: > > syzbot is reporting that memdup_user_nul() which receives user-controlled > > size (which can be up to (INT_MAX & PAGE_MASK)) via vfs_write() will hit > > order >= MAX_ORDER path [1]. > > > > Making costly allocations (order > PAGE_ALLOC_COSTLY_ORDER) naturally fail > > should be better than trying to enforce PAGE_SIZE upper limit, for some of > > callers accept space-delimited list arguments. > > > > Therefore, let's add __GFP_NOWARN to memdup_user_nul() as with > > commit 6c8fcc096be9d02f ("mm: don't let userspace spam allocations > > warnings"). Also use GFP_USER as with other userspace-controllable > > allocations like memdup_user(). > > I absolutely detest hiding this behind __GFP_NOWARN. There should be no > reason to even try hard for memdup_user_nul. Can you explain why this this should have been "try hard to get a physicaly contiguous memory for memdup_user_nul" > cannot use kvmalloc instead? -- Michal Hocko SUSE Labs