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=-3.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 BCD0DC2D0C2 for ; Fri, 3 Jan 2020 17:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92CBD222C3 for ; Fri, 3 Jan 2020 17:47:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KqwmgltC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728220AbgACRrQ (ORCPT ); Fri, 3 Jan 2020 12:47:16 -0500 Received: from mail-lj1-f193.google.com ([209.85.208.193]:33647 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728110AbgACRrQ (ORCPT ); Fri, 3 Jan 2020 12:47:16 -0500 Received: by mail-lj1-f193.google.com with SMTP id y6so36600343lji.0; Fri, 03 Jan 2020 09:47:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=L0RSeiMU8QPdyOoG9B7y/fvlmT9zXEcFUjZ8OB6A7lk=; b=KqwmgltChF4dNJvggsEgsGSiEsBSUXu+bcHz6HLV8dVvSnyVFmshCVm7mtsBYqtA+e 09lS+yhsyGC2JGAGM58yWnZ1eW9V1k6RRebEHZkpy5XkUp5aRONRu0Ih4g9LPfG2iOxE LWBHodFYN1sKKWJEyHuRIPy0YrV39XFdFJ4OgW9ukiK4uRAj3b/nTbLtRtEsC0/YXxGv TsZRgehd1v6WYfO/WFHID9jwuzpblaSKNiLsNtRiGjRl82h8bWpJdTDKpXFLddz049nG eJIxEHqhzRJoNM9NVrJKRGknHmgSeCKXEQ6Ms4gaXH1Jw1WrBOe64KcDWSGVy1Saf/y6 +69g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=L0RSeiMU8QPdyOoG9B7y/fvlmT9zXEcFUjZ8OB6A7lk=; b=ejQ5MRBfASwIEnCTFqMN49bvA78nP+p/M1MJnUwDWbkAHjRTmATirxyV55TrHGHfn1 fwwwIZtJRLkMiVsr8te2uJngRl8vMYpBof/aoF4Cv9CeubrL19LYUVkeXQXFaXJ23e/l ppoT/RtTSMTHkuawMzyN0hoApC6tErMQ+1DTAKTugUi1YOaO30At3diaMgAf44DYhzFh +vBQzPGzw1vW2/hsXFzVeX7sy7Hky12jfHQ6MlkvT4GpEl7T93txmJJvmkZ1VncrpsMd vPOw292SxbXgtYD63c8i/7epNVf8QH1dKUCXNEWmS6/qE9puA2PG0IZG4Ymxj9kuChic OzvA== X-Gm-Message-State: APjAAAVdB0KxAILsQepRrmW4vU+WQ4cuLgKw9Fi8S78R2J0OdgfzUU4U GAwz7sqpXo9FG2W7lbHoLddV8fkWj0vaAfOo2fawZlz9 X-Google-Smtp-Source: APXvYqzVneOWPg55BXdA3ZDaSFLNRTK6aUClojuZRBSWrtYXVqP/JPBgHG7a/2h8VK53E45cVQy+QGViybaJibiKk9g= X-Received: by 2002:a2e:b4cb:: with SMTP id r11mr53035655ljm.68.1578073633455; Fri, 03 Jan 2020 09:47:13 -0800 (PST) MIME-Version: 1.0 References: <20191227215034.3169624-1-guro@fb.com> In-Reply-To: <20191227215034.3169624-1-guro@fb.com> From: Song Liu Date: Fri, 3 Jan 2020 09:47:01 -0800 Message-ID: Subject: Re: [PATCH bpf] bpf: cgroup: prevent out-of-order release of cgroup bpf To: Roman Gushchin Cc: bpf , Alexei Starovoitov , Daniel Borkmann , open list , Kernel Team , Networking , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Dec 27, 2019 at 1:50 PM Roman Gushchin wrote: > > Before commit 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf > from cgroup itself") cgroup bpf structures were released with > corresponding cgroup structures. It guaranteed the hierarchical order > of destruction: children were always first. It preserved attached > programs from being released before their propagated copies. > > But with cgroup auto-detachment there are no such guarantees anymore: > cgroup bpf is released as soon as the cgroup is offline and there are > no live associated sockets. It means that an attached program can be > detached and released, while its propagated copy is still living > in the cgroup subtree. This will obviously lead to an use-after-free > bug. > [...] > > Thanks to Josef Bacik for the debugging and the initial analysis of > the problem. > > Fixes: 4bfc0bb2c60e ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself") > Reported-by: Josef Bacik > Signed-off-by: Roman Gushchin > Cc: Alexei Starovoitov > Cc: stable@vger.kernel.org LGTM. Thanks for the fix! Acked-by: Song Liu