From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751325AbWDYUpA (ORCPT ); Tue, 25 Apr 2006 16:45:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751483AbWDYUpA (ORCPT ); Tue, 25 Apr 2006 16:45:00 -0400 Received: from [198.99.130.12] ([198.99.130.12]:38837 "EHLO saraswathi.solana.com") by vger.kernel.org with ESMTP id S1751325AbWDYUo7 (ORCPT ); Tue, 25 Apr 2006 16:44:59 -0400 Date: Tue, 25 Apr 2006 14:32:51 -0400 From: Jeff Dike To: Bodo Stroesser Cc: Heiko Carstens , linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: [uml-devel] Re: [RFC] PATCH 3/4 - Time virtualization : PTRACE_SYSCALL_MASK Message-ID: <20060425183251.GB22977@ccure.user-mode-linux.org> References: <200604131720.k3DHKqdr004720@ccure.user-mode-linux.org> <20060420090514.GA9452@osiris.boeblingen.de.ibm.com> <444797F8.6020509@fujitsu-siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <444797F8.6020509@fujitsu-siemens.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 20, 2006 at 04:17:28PM +0200, Bodo Stroesser wrote: > Shouldn't 'len' better be the number of bits in the mask than the number of > chars? Yup. > OTOH, I think UML shouldn't send the entire mask, but relevant part only. > The missing end is filled with 0xff by host anyway. So it would be > enough to send the mask up to the highest bit representing a > syscall, that needs to be executed by host. (currently, that is > __NR_gettimeofday). If UML would do so, no more problem results from > UML having a higher NR_syscall than the host (as long as the new > syscalls are to be intercepted and executed by UML) Yup, that was part of the intent of sending in the mask length. > A greater problem might be a process in UML, that calls an invalid syscall > number. AFAICS syscall number (orig_eax) isn't checked before it is > used in do_syscall_trace to address syscall_mask. This might result > in a crash. Yeah, this needs fixing. Heff