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=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 51742C6778A for ; Mon, 2 Jul 2018 20:41:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A74125AB3 for ; Mon, 2 Jul 2018 20:41:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="sl54Btmv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A74125AB3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=efficios.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753307AbeGBUlW (ORCPT ); Mon, 2 Jul 2018 16:41:22 -0400 Received: from mail.efficios.com ([167.114.142.138]:38162 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753121AbeGBUlR (ORCPT ); Mon, 2 Jul 2018 16:41:17 -0400 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 0F60022F23D; Mon, 2 Jul 2018 16:41:17 -0400 (EDT) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id GO_Y7V0B7qmQ; Mon, 2 Jul 2018 16:41:16 -0400 (EDT) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 7490B22F233; Mon, 2 Jul 2018 16:41:16 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 7490B22F233 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1530564076; bh=vIXublIQ6WDadAULnGnU+jj52fEIwRVb5cFCYUhJAOY=; h=From:To:Date:Message-Id; b=sl54BtmvnEtHs/FhXPPK0bbX/iQfpAAQ9rE695RANtiKmPTBYiBt3vLq5Ug+HtjKC D6SRhJsWWE77Uadu12gPnrpe9fsPJ4CNgDjdpYeS2jucUmSnlPiir6TGBi4ojOGQYQ zbvN27TxLXzofj2gpFqWLCjQjOCvgiWNpUHqmA8MfpdlNKqfAmTjSbF80BrBYAh9HA I8W2qdK0dRlCnGmNrxSifMUAOPDB1k2ZGytPxDxBAi3TXWLv+D2MioV8zJ/hqxOInv 4qdL2FEvcYlKsnTRHsL2SL5HH87VSY/RrFkIdhKLpRihQ0odBnRFJCfbVtSUm0XMDB MLeUstHfhLMKg== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10026) with ESMTP id PY3tVCqtHWgO; Mon, 2 Jul 2018 16:41:16 -0400 (EDT) Received: from thinkos.internal.efficios.com (192-222-157-41.qc.cable.ebox.net [192.222.157.41]) by mail.efficios.com (Postfix) with ESMTPSA id 149FA22F227; Mon, 2 Jul 2018 16:41:16 -0400 (EDT) From: Mathieu Desnoyers To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H . Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , Steven Rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes , Mathieu Desnoyers Subject: [RFC PATCH for 4.18 2/2] rseq: validate rseq->rseq_cs padding to be zero Date: Mon, 2 Jul 2018 16:40:58 -0400 Message-Id: <20180702204058.819-2-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180702204058.819-1-mathieu.desnoyers@efficios.com> References: <20180702204058.819-1-mathieu.desnoyers@efficios.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 32-bit kernels, the rseq->rseq_cs_padding field is never read by the kernel. However, 64-bit kernels dealing with 32-bit compat tasks read the full 64-bit in its entirety, and terminates the offending process with a segmentation fault if the upper 32 bits are set due to failure of copy_from_user(). Ensure that both 32-bit and 64-bit kernels dealing with 32-bit tasks end up terminating offending tasks with a segmentation fault if the upper 32-bit padding bits (rseq->rseq_cs_padding) are set by explicitly ensuring that padding is zero on 32-bit kernels. Signed-off-by: Mathieu Desnoyers CC: "Paul E. McKenney" CC: Peter Zijlstra CC: Paul Turner CC: Thomas Gleixner CC: Andy Lutomirski CC: Andi Kleen CC: Dave Watson CC: Chris Lameter CC: Ingo Molnar CC: "H. Peter Anvin" CC: Ben Maurer CC: Steven Rostedt CC: Josh Triplett CC: Linus Torvalds CC: Andrew Morton CC: Russell King CC: Catalin Marinas CC: Will Deacon CC: Michael Kerrisk CC: Boqun Feng CC: linux-api@vger.kernel.org --- kernel/rseq.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/kernel/rseq.c b/kernel/rseq.c index 2e5d88f09baf..c4c48157198f 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -112,6 +112,29 @@ static int rseq_reset_rseq_cpu_id(struct task_struct *t) return 0; } +#ifndef __LP64__ +/* + * Ensure that padding is zero. + */ +static int check_rseq_cs_padding(struct task_struct *t) +{ + unsigned long pad; + int ret; + + ret = __get_user(pad, &t->rseq->rseq_cs_padding); + if (ret) + return ret; + if (pad) + return -EFAULT; + return 0; +} +#else +static int check_rseq_cs_padding(struct task_struct *t) +{ + return 0; +} +#endif + static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) { struct rseq_cs __user *urseq_cs; @@ -123,6 +146,9 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) ret = __get_user(ptr, &t->rseq->rseq_cs); if (ret) return ret; + ret = check_rseq_cs_padding(t); + if (ret) + return ret; if (!ptr) { memset(rseq_cs, 0, sizeof(*rseq_cs)); return 0; -- 2.11.0