Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755229Ab2KIS3o (ORCPT ); Fri, 9 Nov 2012 13:29:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50161 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754503Ab2KIS3n (ORCPT ); Fri, 9 Nov 2012 13:29:43 -0500 Date: Fri, 9 Nov 2012 19:30:26 +0100 From: Oleg Nesterov To: Frederic Weisbecker , Ingo Molnar , Peter Zijlstra Cc: Amnon Shiloh , linux-kernel@vger.kernel.org Subject: Re: [PATCH] arch_check_bp_in_kernelspace: fix the range check Message-ID: <20121109183026.GA2719@redhat.com> References: <20121109182943.GA2789@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121109182943.GA2789@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1232 Lines: 41 On 11/09, Oleg Nesterov wrote: > > Note: TASK_SIZE doesn't look right at least on x86, I think it should > be replaced by TASK_SIZE_MAX. > ... > --- x/arch/x86/kernel/hw_breakpoint.c > +++ x/arch/x86/kernel/hw_breakpoint.c > @@ -200,7 +200,7 @@ int arch_check_bp_in_kernelspace(struct > va = info->address; > len = get_hbp_len(info->len); > > - return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); > + return (va >= TASK_SIZE) || ((va + len - 1) >= TASK_SIZE); But actully I'd like to ask another question. Can't we add the additional !in_gate_area_no_mm() check to allow the hw breakpoints in vsyscall? Quoting Amnon: My service needs to catch the system-calls of its traced son. Almost all system-calls are caught with PTRACE_SYSCALL, but not those using the vsyscall page - especially "gettimeofday()" and "time()". ... However, the code in "arch/x86/kernel/ptrace.c" forbids catching kernel addresses. I tend to agree with Amnon... What do you think? Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/