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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 38052C43603 for ; Tue, 10 Dec 2019 21:28:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B6B6206D5 for ; Tue, 10 Dec 2019 21:28:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="a093tOG7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728887AbfLJV2n (ORCPT ); Tue, 10 Dec 2019 16:28:43 -0500 Received: from mail-pf1-f193.google.com ([209.85.210.193]:46296 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728645AbfLJV2j (ORCPT ); Tue, 10 Dec 2019 16:28:39 -0500 Received: by mail-pf1-f193.google.com with SMTP id y14so448807pfm.13 for ; Tue, 10 Dec 2019 13:28:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :organization:mime-version:content-transfer-encoding; bh=pIRKF4dHpqchckl72/YpmRs/BI55M7i7L1pucxA2z4E=; b=a093tOG7PusILFWMBFDVZ0S7cjLimPfDS0Zqh5j+gZZf0kucIbzeOm1CZHw/ZFdKMP c5BZhT8yU9LDGIwsJooldnJGpXIUeCdvKvmVTV1/7tGguspn6r67Ymp9MWE3b5ABeEX3 MyMvr8rIAhVm4hFS2bpB0VRnNTI9K2aV6dFJnWzCGJ8HOgVy/DnlT2wfZlwVitnqMf1P Izu35iju3ABwkITiAmB6sjvuy0B4D8pxDxbRtihc+tHVaMVUuZKCDNImkk/IPBFMpKcQ ustlUOQPP84kvEv6q34WV3vdg+12dH5JvZzffPU87O63e/lZhpaNqSMeg8mFJh11e3fs c3jA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:organization:mime-version:content-transfer-encoding; bh=pIRKF4dHpqchckl72/YpmRs/BI55M7i7L1pucxA2z4E=; b=GT98UEsyO0J6xZ6VS6lgByhB4mnHTcoGzTD7JsGPEI3Or657xRvO0cFBzcFYPLYcWp N8jQT10eqqmU2hqEDofvsCy3UkM3iCdV/rfgpSVTlHi5jaEz2lcNTIyeMtGICgqkBTxs Zrnl0Q+ANKgy3Jwy71wa6KUccnHo70KlqaahZ0SEf5SGkpOrh7+1IprjZ5TMfPHyw83/ dBcLCvun1tmiMzryGhlUow1s2mD9VjjkOzOPEm4Sj7jBzYaJSwjCYHZX1I9RE+Mvu+Gk BlauKkS5Bf7rqz8XcE2x08xEoSeBjGHem3ZVSIjKO3AcmVCjqeOVva4bORF+xUCJFilN FqnQ== X-Gm-Message-State: APjAAAUjm8jOfg/EnifCENs9VL7k0tzMrpukDX55R9XjeFuQS1f3ORRX iX/OkVwmWT6jMSeK7/N6matI2VbBDOw= X-Google-Smtp-Source: APXvYqxRq/2Ns0jfcbuRphOE4p7vfQeBo99PSUxKfImVcOh2PMEHsuUBN+Tqjb4WlMMGrECKyUA6ww== X-Received: by 2002:a63:e608:: with SMTP id g8mr190645pgh.448.1576013318350; Tue, 10 Dec 2019 13:28:38 -0800 (PST) Received: from cakuba.netronome.com ([66.60.152.14]) by smtp.gmail.com with ESMTPSA id k4sm4629761pfk.11.2019.12.10.13.28.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Dec 2019 13:28:38 -0800 (PST) Date: Tue, 10 Dec 2019 13:28:34 -0800 From: Jakub Kicinski To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Andrii Nakryiko , Daniel Borkmann , Song Liu , netdev@vger.kernel.org, bpf@vger.kernel.org, oss-drivers@netronome.com Subject: Re: [oss-drivers] [PATCH AUTOSEL 5.4 326/350] bpf: Switch bpf_map ref counter to atomic64_t so bpf_map_inc() never fails Message-ID: <20191210132834.157d5fc5@cakuba.netronome.com> In-Reply-To: <20191210210735.9077-287-sashal@kernel.org> References: <20191210210735.9077-1-sashal@kernel.org> <20191210210735.9077-287-sashal@kernel.org> Organization: Netronome Systems, Ltd. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Dec 2019 16:07:11 -0500, Sasha Levin wrote: > From: Andrii Nakryiko > > [ Upstream commit 1e0bd5a091e5d9e0f1d5b0e6329b87bb1792f784 ] > > 92117d8443bc ("bpf: fix refcnt overflow") turned refcounting of bpf_map into > potentially failing operation, when refcount reaches BPF_MAX_REFCNT limit > (32k). Due to using 32-bit counter, it's possible in practice to overflow > refcounter and make it wrap around to 0, causing erroneous map free, while > there are still references to it, causing use-after-free problems. I don't think this is a bug fix, the second sentence here is written in a quite confusing way, but there is no bug. Could you drop? I don't think it's worth the backporting pain since it changes bpf_map_inc().