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 EE57CC31E4B for ; Fri, 14 Jun 2019 12:10:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D07D7208CA for ; Fri, 14 Jun 2019 12:10:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727635AbfFNMKm convert rfc822-to-8bit (ORCPT ); Fri, 14 Jun 2019 08:10:42 -0400 Received: from mail-ed1-f65.google.com ([209.85.208.65]:38296 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727692AbfFNMKm (ORCPT ); Fri, 14 Jun 2019 08:10:42 -0400 Received: by mail-ed1-f65.google.com with SMTP id r12so996346edo.5 for ; Fri, 14 Jun 2019 05:10:41 -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=XLlLHksTC0yxOESsFyxxxiYxkKN8pdc2F58BlGgcWg0=; b=QPl57m4fNaX48L5x5VR6PrOBvnL7S5JCnbljXhO2TgvKI8k75W4xcx695WTyEf8zJB AZraasMeJNLCDxe0Un+/FxPzjLQKvCpk/U0S23E8+DPac6ql5GIGI8S7T8OKcjwyzdvc Lts0e7kMe0E1gMZ84BvzsB39hnP5jrDy3dLsy4YoMal3LQDHbBZ73S39InWalzVtolJX 5Lay8p5UOCG/dpPWLVmr7QLm0+1KWkCBoZkRdIZCTlfti+pVhVy3weIhuT8CcCUwCGJg 6PVpifH+aag1lHsQlu/Cu7biUScorK4Lt6WQslHlq2jne05VjTu+5kg8nz7H+SyXRcyL JDRw== X-Gm-Message-State: APjAAAUPuzPEvZb+kkHEhaveeiVX3Q4snzwzbDltTlTxXlRLrS63jDDM /kLmqvw+OFKoDId5X8muK0rasg== X-Google-Smtp-Source: APXvYqxoNbtKbpy/btptoDlq7ip+Nw9Gj+2UeqoGWBE6r0aFpGw8qJdyH+25ljIk33c3tAmmbbEzHg== X-Received: by 2002:a17:906:5a48:: with SMTP id l8mr34249129ejs.169.1560514240496; Fri, 14 Jun 2019 05:10:40 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk (borgediget.toke.dk. [85.204.121.218]) by smtp.gmail.com with ESMTPSA id l6sm860802edk.8.2019.06.14.05.10.39 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 05:10:39 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id 37D681804AF; Fri, 14 Jun 2019 14:10:38 +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: Toshiaki Makita , 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: <877e9octre.fsf@toke.dk> References: <20190614082015.23336-1-toshiaki.makita1@gmail.com> <20190614082015.23336-2-toshiaki.makita1@gmail.com> <877e9octre.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Fri, 14 Jun 2019 14:10:38 +0200 Message-ID: <87sgscbc5d.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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? -Toke