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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 4A5CCC432C3 for ; Wed, 27 Nov 2019 21:31:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14CE2206F0 for ; Wed, 27 Nov 2019 21:31:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574890283; bh=eaBjrtbhJ62pLWppLNZsKpx+Q5x1JcT00JxRyiiPxLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X/hZLEeKmfF7ZwCHvl0J+ib6hbsQxNSzWJJxTIct2FoWNkeAIqshBTLMQhA0/tzvF gVQ2M09QT3oeB0jJnCwRHoG2IF/Dx6TUsFr1HdwH/7oIXIww2H2XNfcbeQgDKqdW8b I6PePit1SP6AJWEhLDEIZRwrjo1EFswk/Tg9zodI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730916AbfK0VbW (ORCPT ); Wed, 27 Nov 2019 16:31:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:45036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730866AbfK0Uyp (ORCPT ); Wed, 27 Nov 2019 15:54:45 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6EDFF2086A; Wed, 27 Nov 2019 20:54:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574888084; bh=eaBjrtbhJ62pLWppLNZsKpx+Q5x1JcT00JxRyiiPxLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QQ+Ur8RxTHX6nNXmsLPWUxQJv3riqMujx7FOqjE3j4Ol4v9w6z6e6CrvUGArBGhtp MlkFwi15vHT1bc9jag/eOIb0gyESleSdmBrdyW7PDEOY9W6RxHjb1eRY/W41iFRPS3 E4V8VnkqXcMERSmv8gjUN0YQvqb9okbvhig4f3as= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , "Peter Zijlstra (Intel)" , stable@kernel.org Subject: [PATCH 4.14 183/211] selftests/x86/mov_ss_trap: Fix the SYSENTER test Date: Wed, 27 Nov 2019 21:31:56 +0100 Message-Id: <20191127203111.057361704@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203049.431810767@linuxfoundation.org> References: <20191127203049.431810767@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski commit 8caa016bfc129f2c925d52da43022171d1d1de91 upstream. For reasons that I haven't quite fully diagnosed, running mov_ss_trap_32 on a 32-bit kernel results in an infinite loop in userspace. This appears to be because the hacky SYSENTER test doesn't segfault as desired; instead it corrupts the program state such that it infinite loops. Fix it by explicitly clearing EBP before doing SYSENTER. This will give a more reliable segfault. Fixes: 59c2a7226fc5 ("x86/selftests: Add mov_to_ss test") Signed-off-by: Andy Lutomirski Signed-off-by: Peter Zijlstra (Intel) Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- tools/testing/selftests/x86/mov_ss_trap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/tools/testing/selftests/x86/mov_ss_trap.c +++ b/tools/testing/selftests/x86/mov_ss_trap.c @@ -257,7 +257,8 @@ int main() err(1, "sigaltstack"); sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND | SA_ONSTACK); nr = SYS_getpid; - asm volatile ("mov %[ss], %%ss; SYSENTER" : "+a" (nr) + /* Clear EBP first to make sure we segfault cleanly. */ + asm volatile ("xorl %%ebp, %%ebp; mov %[ss], %%ss; SYSENTER" : "+a" (nr) : [ss] "m" (ss) : "flags", "rcx" #ifdef __x86_64__ , "r11"