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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 EC6FAC433E1 for ; Mon, 29 Jun 2020 20:34:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CAD75207FF for ; Mon, 29 Jun 2020 20:34:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593462851; bh=0TIgXh0UJBp6NZVUlhYfT7EIO63h8jLGw0n+lEZnSD8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CzYZS9FecM2UmqZ1uhe1NpsZmkcg0dOgwb3oO7BX3KSS/9EiNBRwhCATop521rJZw HPT//Kzg9/foaw1lXs7UtZqTZG2LSm6s7xP2QE7IOT2ZkHByuOnPnNBYlcH+5QNQvf NxQ8lNjtviX5YtTiNR9gtHJq3MZVNH56qfdNh0xQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388957AbgF2Udy (ORCPT ); Mon, 29 Jun 2020 16:33:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732293AbgF2TZQ (ORCPT ); Mon, 29 Jun 2020 15:25:16 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9F193253E4; Mon, 29 Jun 2020 15:42:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593445323; bh=0TIgXh0UJBp6NZVUlhYfT7EIO63h8jLGw0n+lEZnSD8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ENbNF3ZVOXFhPnNTN5KKHqP7j3bc/USJxzSGJztKMaJ1vYwJWHMStFgheP1ftPq7R VF+qJ7PshSfHODGDX5774jF10xscracrdc6xF7XbavyA5/gaPle2D9Kob9K4sowYMu YywiP6kIQTW5TAshg2TMeVBPiRlEet63Vp/H1ils= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Dmitry V. Levin" , Elvira Khabirova , Heiko Carstens , Vasily Gorbik , Greg Kroah-Hartman Subject: [PATCH 4.9 089/191] s390: fix syscall_get_error for compat processes Date: Mon, 29 Jun 2020 11:38:25 -0400 Message-Id: <20200629154007.2495120-90-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629154007.2495120-1-sashal@kernel.org> References: <20200629154007.2495120-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.9.229-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.9.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.9.229-rc1 X-KernelTest-Deadline: 2020-07-01T15:39+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Dmitry V. Levin" commit b3583fca5fb654af2cfc1c08259abb9728272538 upstream. If both the tracer and the tracee are compat processes, and gprs[2] is assigned a value by __poke_user_compat, then the higher 32 bits of gprs[2] are cleared, IS_ERR_VALUE() always returns false, and syscall_get_error() always returns 0. Fix the implementation by sign-extending the value for compat processes the same way as x86 implementation does. The bug was exposed to user space by commit 201766a20e30f ("ptrace: add PTRACE_GET_SYSCALL_INFO request") and detected by strace test suite. This change fixes strace syscall tampering on s390. Link: https://lkml.kernel.org/r/20200602180051.GA2427@altlinux.org Fixes: 753c4dd6a2fa2 ("[S390] ptrace changes") Cc: Elvira Khabirova Cc: stable@vger.kernel.org # v2.6.28+ Signed-off-by: Dmitry V. Levin Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/include/asm/syscall.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h index 6bc941be69217..166fbd74e316c 100644 --- a/arch/s390/include/asm/syscall.h +++ b/arch/s390/include/asm/syscall.h @@ -41,7 +41,17 @@ static inline void syscall_rollback(struct task_struct *task, static inline long syscall_get_error(struct task_struct *task, struct pt_regs *regs) { - return IS_ERR_VALUE(regs->gprs[2]) ? regs->gprs[2] : 0; + unsigned long error = regs->gprs[2]; +#ifdef CONFIG_COMPAT + if (test_tsk_thread_flag(task, TIF_31BIT)) { + /* + * Sign-extend the value so (int)-EFOO becomes (long)-EFOO + * and will match correctly in comparisons. + */ + error = (long)(int)error; + } +#endif + return IS_ERR_VALUE(error) ? error : 0; } static inline long syscall_get_return_value(struct task_struct *task, -- 2.25.1