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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 48C7AC31E4D for ; Fri, 14 Jun 2019 13:09:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B6BC21537 for ; Fri, 14 Jun 2019 13:09:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727970AbfFNNJt convert rfc822-to-8bit (ORCPT ); Fri, 14 Jun 2019 09:09:49 -0400 Received: from mail-lj1-f193.google.com ([209.85.208.193]:33057 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727949AbfFNNJt (ORCPT ); Fri, 14 Jun 2019 09:09:49 -0400 Received: by mail-lj1-f193.google.com with SMTP id h10so2374534ljg.0 for ; Fri, 14 Jun 2019 06:09:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=Is2zt4xuPWFEApbl5ORBmK+IPfz3ajAdFURJMG4yxiY=; b=pz2parMkYAJeTu0DjKCHu1uJaEqwdv8PmJ9MUIdPTzOChsS0LSk1vOO4Mfe/Y42+cc zhIrmfAggKE5B8Y5Myi403q81qWpTug2XWk/jABmIMWmWVEn8JJhiEf9moiFpl3+ZnFh 37Quj4O17UwRnl5YRx92kVyhbjgKQHs2A9DJrw06M2jHrW2ALc0T8nj++uu4VirfjJvw pixL/xEA7wicTFB0wsNFX6EGU8/clJO7gxgnf9/YnSlleV2podD9zymxj4lgOtG4YUvY ih7vdrlksp+VRXrEYGpcLg5xM6kAcGWVIgh7VKjpaATDfsOHn5+3pK9rxzMGOJ84hI8e iTpA== X-Gm-Message-State: APjAAAVjsR77mExHggfRnl4LqE3Nd+cLW2V1IS+6ZJA/94pjb+og9J9d vNvN2uS55nvScCPvx/sdhFzB2Q== X-Google-Smtp-Source: APXvYqy72eIYPlb2FmXUPnqstUqE4swr4j71twVWOCQULDu7nh6B1rq+hQAZn+NfTS9xe6oOaOf67A== X-Received: by 2002:a2e:9198:: with SMTP id f24mr4297835ljg.221.1560517786638; Fri, 14 Jun 2019 06:09:46 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk (borgediget.toke.dk. [85.204.121.218]) by smtp.gmail.com with ESMTPSA id 25sm587526ljn.62.2019.06.14.06.09.45 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 06:09:45 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id D6EC31804AF; Fri, 14 Jun 2019 15:09:44 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Toshiaki Makita , Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend Cc: netdev@vger.kernel.org, xdp-newbies@vger.kernel.org, bpf@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , David Ahern Subject: Re: [PATCH bpf 1/3] devmap: Fix premature entry free on destroying map In-Reply-To: References: <20190614082015.23336-1-toshiaki.makita1@gmail.com> <20190614082015.23336-2-toshiaki.makita1@gmail.com> <877e9octre.fsf@toke.dk> <87sgscbc5d.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 14 Jun 2019 15:09:44 +0200 Message-ID: <87muikb9ev.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Toshiaki Makita writes: > On 19/06/14 (金) 21:10:38, Toke Høiland-Jørgensen wrote: >> Toke Høiland-Jørgensen writes: >> >>> Toshiaki Makita writes: >>> >>>> dev_map_free() waits for flush_needed bitmap to be empty in order to >>>> ensure all flush operations have completed before freeing its entries. >>>> However the corresponding clear_bit() was called before using the >>>> entries, so the entries could be used after free. >>>> >>>> All access to the entries needs to be done before clearing the bit. >>>> It seems commit a5e2da6e9787 ("bpf: netdev is never null in >>>> __dev_map_flush") accidentally changed the clear_bit() and memory access >>>> order. >>>> >>>> Note that the problem happens only in __dev_map_flush(), not in >>>> dev_map_flush_old(). dev_map_flush_old() is called only after nulling >>>> out the corresponding netdev_map entry, so dev_map_free() never frees >>>> the entry thus no such race happens there. >>>> >>>> Fixes: a5e2da6e9787 ("bpf: netdev is never null in __dev_map_flush") >>>> Signed-off-by: Toshiaki Makita >>> >>> I recently posted a patch[0] that gets rid of the bitmap entirely, so I >>> think you can drop this one... >> >> Alternatively, since this entire series should probably go to stable, I >> can respin mine on top of it? > > Indeed conflict will happen, as this is for 'bpf' not 'bpf-next'. > Sorry for disturbing your work. Oh, no worries! > I'm also not sure how to proceed in this case. I guess we'll leave that up to the maintainers :) -Toke