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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=unavailable 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 0C642C433DB for ; Tue, 16 Mar 2021 11:53:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D27D865058 for ; Tue, 16 Mar 2021 11:53:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237506AbhCPLxI (ORCPT ); Tue, 16 Mar 2021 07:53:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:58294 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229826AbhCPLww (ORCPT ); Tue, 16 Mar 2021 07:52:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B988CAE56; Tue, 16 Mar 2021 11:52:50 +0000 (UTC) Date: Tue, 16 Mar 2021 12:52:48 +0100 From: Borislav Petkov To: "Chang S. Bae" Cc: tglx@linutronix.de, mingo@kernel.org, luto@kernel.org, x86@kernel.org, len.brown@intel.com, dave.hansen@intel.com, hjl.tools@gmail.com, Dave.Martin@arm.com, jannh@google.com, mpe@ellerman.id.au, carlos@redhat.com, tony.luck@intel.com, ravi.v.shankar@intel.com, libc-alpha@sourceware.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 5/6] x86/signal: Detect and prevent an alternate signal stack overflow Message-ID: <20210316115248.GB18822@zn.tnic> References: <20210316065215.23768-1-chang.seok.bae@intel.com> <20210316065215.23768-6-chang.seok.bae@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210316065215.23768-6-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 15, 2021 at 11:52:14PM -0700, Chang S. Bae wrote: > @@ -272,7 +275,8 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, > * 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 (onsigstack && !likely(on_sig_stack(sp))) > + if (onsigstack && unlikely(sp <= current->sas_ss_sp || > + sp - current->sas_ss_sp > current->sas_ss_size)) > return (void __user *)-1L; So clearly I'm missing something because trying to trigger the test case in the bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=153531 on current tip/master doesn't work. Runs with MY_MINSIGSTKSZ under 2048 fail with: tst-minsigstksz-2: sigaltstack: Cannot allocate memory and above 2048 don't overwrite bytes below the stack. So something else is missing. How did you test this patch? Thx. -- Regards/Gruss, Boris. SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg