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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 3BB4BC41514 for ; Wed, 4 Sep 2019 11:49:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EB1C22CF7 for ; Wed, 4 Sep 2019 11:49:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725829AbfIDLth (ORCPT ); Wed, 4 Sep 2019 07:49:37 -0400 Received: from foss.arm.com ([217.140.110.172]:52778 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729664AbfIDLth (ORCPT ); Wed, 4 Sep 2019 07:49:37 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 82ADE337; Wed, 4 Sep 2019 04:49:36 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9B3C83F246; Wed, 4 Sep 2019 04:49:35 -0700 (PDT) Date: Wed, 4 Sep 2019 12:49:33 +0100 From: Dave Martin To: Cristian Marussi Cc: linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, shuah@kernel.org, amit.kachhap@arm.com, andreyknvl@google.com Subject: Re: [PATCH v5 10/11] kselftest: arm64: fake_sigreturn_bad_size Message-ID: <20190904114933.GA27757@arm.com> References: <20190902112932.36129-1-cristian.marussi@arm.com> <20190902112932.36129-11-cristian.marussi@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190902112932.36129-11-cristian.marussi@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Mon, Sep 02, 2019 at 12:29:31pm +0100, Cristian Marussi wrote: > Add a simple fake_sigreturn testcase which builds a ucontext_t with a > badly sized header that causes a overrun in the __reserved area and > place it onto the stack. Expects a SIGSEGV on test PASS. > > Signed-off-by: Cristian Marussi > --- > v3 --> v4 > - fix commit > - missing include > - using new get_starting_head() helper > - added test description > --- > .../testcases/fake_sigreturn_bad_size.c | 77 +++++++++++++++++++ > 1 file changed, 77 insertions(+) > create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c > > diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c > new file mode 100644 > index 000000000000..b1156afdb691 > --- /dev/null > +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c > @@ -0,0 +1,77 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2019 ARM Limited > + * > + * Place a fake sigframe on the stack including a bad record overflowing > + * the __reserved space: on sigreturn Kernel must spot this attempt and > + * the test case is expected to be terminated via SEGV. > + */ > + > +#include > +#include > + > +#include "test_signals_utils.h" > +#include "testcases.h" > + > +struct fake_sigframe sf; > + > +#define MIN_SZ_ALIGN 16 > + > +static int fake_sigreturn_bad_size_run(struct tdescr *td, > + siginfo_t *si, ucontext_t *uc) > +{ > + size_t resv_sz, need_sz, offset; > + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; > + > + /* just to fill the ucontext_t with something real */ > + if (!get_current_context(td, &sf.uc)) > + return 1; > + > + resv_sz = GET_SF_RESV_SIZE(sf); > + /* at least HDR_SZ + bad sized esr_context needed */ > + need_sz = HDR_SZ + sizeof(struct esr_context); Nit: can we write this sum the other way round (see comment on patch 9)? > + head = get_starting_head(shead, need_sz, resv_sz, &offset); > + if (head) { > + /* > + * Use an esr_context to build a fake header with a > + * size greater then the free __reserved area minus HDR_SZ; > + * using ESR_MAGIC here since it is not checked for size nor > + * is limited to one instance. > + * > + * At first inject an additional normal esr_context > + */ > + head->magic = ESR_MAGIC; > + head->size = sizeof(struct esr_context); > + /* and terminate properly */ > + write_terminator_record(GET_RESV_NEXT_HEAD(head)); > + ASSERT_GOOD_CONTEXT(&sf.uc); > + > + /* > + * now mess with fake esr_context size: leaving less space than > + * needed while keeping size value 16-aligned > + * > + * It must trigger a SEGV from Kernel on: > + * > + * resv_sz - offset < sizeof(*head) > + */ > + /* at first set the maximum good 16-aligned size */ > + head->size = > + (resv_sz - offset - need_sz + MIN_SZ_ALIGN) & ~0xfUL; > + /* plus a bit more of 16-aligned sized stuff */ > + head->size += MIN_SZ_ALIGN; Can we also have versions of this test that try: a) a size that doesn't overflow __reserved[], but is not a multiple of 16 b) a size that is less than 16 c) a size that does overflow __reserved[], but by less than 16 bytes? These tests are all closely related and can probably be macro-ised easily. They can go on the TODO list for now anyway: let's get this series settled in its current form first. In any case: Reviewed-by: Dave Martin