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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 BB55DC43387 for ; Wed, 9 Jan 2019 06:33:03 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 446B22070B for ; Wed, 9 Jan 2019 06:33:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 446B22070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 43ZK7d3RB6zDqdp for ; Wed, 9 Jan 2019 17:33:01 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=c-s.fr (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@c-s.fr; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 43ZK5l539hzDqZm for ; Wed, 9 Jan 2019 17:31:23 +1100 (AEDT) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 43ZK5f5s3KzB09Zp; Wed, 9 Jan 2019 07:31:18 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id EwtYdEygmGE5; Wed, 9 Jan 2019 07:31:18 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 43ZK5f5JQKzB09Zn; Wed, 9 Jan 2019 07:31:18 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 916578B7F0; Wed, 9 Jan 2019 07:31:19 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id Xfv5UHXxnK9N; Wed, 9 Jan 2019 07:31:19 +0100 (CET) Received: from PO15451 (po15451.idsi0.si.c-s.fr [172.25.231.3]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A05F38B7EA; Wed, 9 Jan 2019 07:31:18 +0100 (CET) Subject: Re: [PATCH] lkdtm: Add a tests for NULL pointer dereference To: Kees Cook References: <8593f7faf89812a9987d44d9ae615d64dca4d77f.1544800744.git.christophe.leroy@c-s.fr> From: Christophe Leroy Message-ID: <2d2e8cef-dd12-75e8-4779-fe4437e2169c@c-s.fr> Date: Wed, 9 Jan 2019 07:31:17 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Greg Kroah-Hartman , PowerPC , LKML , Arnd Bergmann Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 09/01/2019 à 02:14, Kees Cook a écrit : > On Fri, Dec 14, 2018 at 7:26 AM Christophe Leroy > wrote: >> >> Introduce lkdtm tests for NULL pointer dereference: check >> access or exec at NULL address. > > Why is this not already covered by the existing tests? (Is there > something special about NULL that is being missed?) I'd expect SMAP > and SMEP to cover NULL as well. Most arches print a different message whether the faulty address is above or under PAGE_SIZE. Below is exemple from x86: pr_alert("BUG: unable to handle kernel %s at %px\n", address < PAGE_SIZE ? "NULL pointer dereference" : "paging request", (void *)address); Until recently, the powerpc arch didn't do it. When I implemented it (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=49a502ea23bf9dec47f8f3c3960909ff409cd1bb), I needed a way to test it and couldn't find an existing one, hence this new LKDTM test. But maybe I missed something ? Christophe > > -Kees > >> >> Signed-off-by: Christophe Leroy >> --- >> drivers/misc/lkdtm/core.c | 2 ++ >> drivers/misc/lkdtm/lkdtm.h | 2 ++ >> drivers/misc/lkdtm/perms.c | 18 ++++++++++++++++++ >> 3 files changed, 22 insertions(+) >> >> diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c >> index bc76756b7eda..36910e1d5c09 100644 >> --- a/drivers/misc/lkdtm/core.c >> +++ b/drivers/misc/lkdtm/core.c >> @@ -157,7 +157,9 @@ static const struct crashtype crashtypes[] = { >> CRASHTYPE(EXEC_VMALLOC), >> CRASHTYPE(EXEC_RODATA), >> CRASHTYPE(EXEC_USERSPACE), >> + CRASHTYPE(EXEC_NULL), >> CRASHTYPE(ACCESS_USERSPACE), >> + CRASHTYPE(ACCESS_NULL), >> CRASHTYPE(WRITE_RO), >> CRASHTYPE(WRITE_RO_AFTER_INIT), >> CRASHTYPE(WRITE_KERN), >> diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h >> index 3c6fd327e166..b69ee004a3f7 100644 >> --- a/drivers/misc/lkdtm/lkdtm.h >> +++ b/drivers/misc/lkdtm/lkdtm.h >> @@ -45,7 +45,9 @@ void lkdtm_EXEC_KMALLOC(void); >> void lkdtm_EXEC_VMALLOC(void); >> void lkdtm_EXEC_RODATA(void); >> void lkdtm_EXEC_USERSPACE(void); >> +void lkdtm_EXEC_NULL(void); >> void lkdtm_ACCESS_USERSPACE(void); >> +void lkdtm_ACCESS_NULL(void); >> >> /* lkdtm_refcount.c */ >> void lkdtm_REFCOUNT_INC_OVERFLOW(void); >> diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c >> index fa54add6375a..62f76d506f04 100644 >> --- a/drivers/misc/lkdtm/perms.c >> +++ b/drivers/misc/lkdtm/perms.c >> @@ -164,6 +164,11 @@ void lkdtm_EXEC_USERSPACE(void) >> vm_munmap(user_addr, PAGE_SIZE); >> } >> >> +void lkdtm_EXEC_NULL(void) >> +{ >> + execute_location(NULL, CODE_AS_IS); >> +} >> + >> void lkdtm_ACCESS_USERSPACE(void) >> { >> unsigned long user_addr, tmp = 0; >> @@ -195,6 +200,19 @@ void lkdtm_ACCESS_USERSPACE(void) >> vm_munmap(user_addr, PAGE_SIZE); >> } >> >> +void lkdtm_ACCESS_NULL(void) >> +{ >> + unsigned long tmp; >> + unsigned long *ptr = (unsigned long *)NULL; >> + >> + pr_info("attempting bad read at %px\n", ptr); >> + tmp = *ptr; >> + tmp += 0xc0dec0de; >> + >> + pr_info("attempting bad write at %px\n", ptr); >> + *ptr = tmp; >> +} >> + >> void __init lkdtm_perms_init(void) >> { >> /* Make sure we can write to __ro_after_init values during __init */ >> -- >> 2.13.3 >> > >