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=-5.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 4A92BC0650E for ; Mon, 1 Jul 2019 18:25:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 196922146F for ; Mon, 1 Jul 2019 18:25:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="Ehn/I4B4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726587AbfGASZW (ORCPT ); Mon, 1 Jul 2019 14:25:22 -0400 Received: from mail-pg1-f193.google.com ([209.85.215.193]:36991 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbfGASZW (ORCPT ); Mon, 1 Jul 2019 14:25:22 -0400 Received: by mail-pg1-f193.google.com with SMTP id g15so4525299pgi.4 for ; Mon, 01 Jul 2019 11:25:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=727aBBfWqYrKy3zdRdkTXxLgWwNQre9utWIB8UaiK2g=; b=Ehn/I4B4HkIjvHy6V9HxTRXh3F8YWylu8ympYyLVqIQxwF/qtaM/RDmkvNnTNQbdoQ MOFe3neeigVp0ZlIqijol7rr9IKmlQzgxVUOy++18cE2QEElAiMYSoOcKxqTNtyQ1PG0 z6axRHN3bwo8z7KVbfu0m/73XA9Bx+wc8BqyI= 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:references :mime-version:content-disposition:in-reply-to:user-agent; bh=727aBBfWqYrKy3zdRdkTXxLgWwNQre9utWIB8UaiK2g=; b=pMRTCgRN8JFwMh0V3KgB8OCxOG7OHR8hVRFB5jzR/mARZnK8OlSFAwqEfdA0dPQXAm pG1eAZzOgFi4aasGEg3v+NmLtFpWDL2sk+aL9lvpdXNF0hyeBpC/XiKZbMvD4u737f1F LrVy+4P0PckUxksUwZxwjRdyOAkTi2mJ7eLLoW/qVyziItWL6EcDnEs/6XGk7jsRdfHT euPRaEMthhBJXc9440WV1Ni+TodZbWXdbo5vaZ3uCdxfbSFjA731a4NLQkamvJkR36Xj 3Xxbas4sYYeV4omJKl9zBE7vy/oEt9IU9KcgWu+c8/ZPgCK3MuoXIYxm2bLvMNhfBp6j vAlA== X-Gm-Message-State: APjAAAXx154qPG3r3vfqVGDWwRwxm2HReWEZwyuHD0THVNIzJSFL5OWX ieLe4JhTaz/6J6Nk74zVKXpYxw== X-Google-Smtp-Source: APXvYqxbjX3RJLpO0anArjOh5JUBRzWK/fY7e05ZbhUnH9NIahw6rvOQWHz+4F/sxkMdBuuda3lNGg== X-Received: by 2002:a63:7b18:: with SMTP id w24mr22771702pgc.328.1562005521251; Mon, 01 Jul 2019 11:25:21 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id y68sm12576238pfy.164.2019.07.01.11.25.20 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 01 Jul 2019 11:25:20 -0700 (PDT) Date: Mon, 1 Jul 2019 14:25:19 -0400 From: Joel Fernandes To: Jann Horn Cc: kernel list , Mathieu Desnoyers , Matthew Wilcox , Peter Zijlstra , Will Deacon , "Paul E . McKenney" , Elena Reshetova , Kees Cook , kernel-team , Kernel Hardening , Andrew Morton , "Eric W. Biederman" , Michal Hocko , Oleg Nesterov , Stephen Rothwell Subject: Re: [PATCH v2] Convert struct pid count to refcount_t Message-ID: <20190701182519.GA125555@google.com> References: <20190628193442.94745-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 01, 2019 at 07:48:26PM +0200, Jann Horn wrote: > On Fri, Jun 28, 2019 at 9:35 PM Joel Fernandes (Google) > wrote: > > struct pid's count is an atomic_t field used as a refcount. Use > > refcount_t for it which is basically atomic_t but does additional > > checking to prevent use-after-free bugs. > [...] > > struct pid > > { > > - atomic_t count; > > + refcount_t count; > [...] > > diff --git a/kernel/pid.c b/kernel/pid.c > > index 20881598bdfa..89c4849fab5d 100644 > > --- a/kernel/pid.c > > +++ b/kernel/pid.c > > @@ -37,7 +37,7 @@ > > #include > > #include > > #include > > -#include > > +#include > > #include > > #include > > > > @@ -106,8 +106,7 @@ void put_pid(struct pid *pid) > > init_struct_pid is defined as follows: > > struct pid init_struct_pid = { > .count = ATOMIC_INIT(1), > [...] > }; > > This should be changed to REFCOUNT_INIT(1). > > You should have received a compiler warning about this; I get the > following when trying to build with your patch applied: Thanks. Andrew had fixed this in patch v1 but Linus dropped it for other reasons. Anyway, I should have fixed this in my resubmit. Sorry, I'll fix and resend! - Joel