Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761481AbYBSCV3 (ORCPT ); Mon, 18 Feb 2008 21:21:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756208AbYBSCVV (ORCPT ); Mon, 18 Feb 2008 21:21:21 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:55030 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755693AbYBSCVU (ORCPT ); Mon, 18 Feb 2008 21:21:20 -0500 Message-ID: <47BA3CAB.30905@cn.fujitsu.com> Date: Tue, 19 Feb 2008 10:19:23 +0800 From: Shi Weihua User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Ingo Molnar CC: linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" Subject: Re: [PATCH 1/5] signal(x86_32): Improve the signal stack overflow check References: <47B95C4D.6080000@cn.fujitsu.com> In-Reply-To: <47B95C4D.6080000@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 48 We need to check for stack overflow only when the signal is on stack. So we can improve the patch "http://lkml.org/lkml/2007/11/27/101" as following. Signed-off-by: Shi Weihua --- The previous patch has a comment mistake. Now I correct it. --- --- linux-2.6.25-rc2.orig/arch/x86/kernel/signal_32.c 2008-02-16 04:57:20.000000000 +0800 +++ linux-2.6.25-rc2/arch/x86/kernel/signal_32.c 2008-02-19 09:55:59.000000000 +0800 @@ -299,17 +299,21 @@ get_sigframe(struct k_sigaction *ka, str /* Default to using normal stack */ sp = regs->sp; - /* - * If we are on the alternate signal stack and would overflow it, don't. - * Return an always-bogus address instead so we will die with SIGSEGV. - */ - if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size))) - return (void __user *) -1L; - /* This is the X/Open sanctioned signal stack switching. */ if (ka->sa.sa_flags & SA_ONSTACK) { - if (sas_ss_flags(sp) == 0) + int onstack = sas_ss_flags(sp); + + if (onstack == 0) sp = current->sas_ss_sp + current->sas_ss_size; + else if (onstack == SS_ONSTACK) { + /* + * If we are on the alternate signal stack and would + * overflow it, don't. Return an always-bogus address + * instead so we will die with SIGSEGV. + */ + if (!likely(on_sig_stack(sp - frame_size))) + return (void __user *) -1L; + } } /* This is the legacy signal stack switching. */ -- 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/