From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753783Ab1IJXei (ORCPT ); Sat, 10 Sep 2011 19:34:38 -0400 Received: from mail-pz0-f42.google.com ([209.85.210.42]:46506 "EHLO mail-pz0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751022Ab1IJXeh (ORCPT ); Sat, 10 Sep 2011 19:34:37 -0400 Date: Sun, 11 Sep 2011 08:34:31 +0900 From: Tejun Heo To: Denys Vlasenko Cc: Oleg Nesterov , linux-kernel@vger.kernel.org, Denys Vlasenko Subject: Re: [PATCH v3] Make PTRACE_SEIZE set ptrace options specified in 'data' Message-ID: <20110910233431.GD29319@htj.dyndns.org> References: <1315506333.18043.49.camel@dhcp-25-63.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1315506333.18043.49.camel@dhcp-25-63.brq.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 08, 2011 at 08:22:04PM +0200, Denys Vlasenko wrote: > Make PTRACE_SEIZE set ptrace options specified in 'data' parameter > > This can be used to close a few corner cases in strace where we get > unwanted racy behavior after attach, but before we have a chance > to set options (the notorious post-execve SIGTRAP comes to mind), > and removes the need to track "did we set opts for this task" state > in strace internals. > > While we are at it: > > Make it possible to extend SEIZE in the future with more functionality > by passing non-zero 'addr' parameter. > To that end, error out if 'addr' is non-zero. > PTRACE_ATTACH did not (and still does not) have such check, > and users (strace) do pass garbage there... let's avoid repeating > this mistake with SEIZE. > > Set all task->ptrace bits in one operation - before this change, > we were adding PT_SEIZED and PT_PTRACE_CAP with task->ptrace |= BIT ops. > This was probably ok (not a bug), but let's be on a safer side. > > Changes since v2: use (unsigned long) casts instead of (long) ones, > move PTRACE_SEIZE_DEVEL-related code to separate lines of code. > > > Signed-off-by: Denys Vlasenko Acked-by: Tejun Heo Thanks. -- tejun