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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 253BBC71156 for ; Fri, 20 Nov 2020 11:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D03B02240C for ; Fri, 20 Nov 2020 11:04:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jF5X2d8U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728013AbgKTLEj (ORCPT ); Fri, 20 Nov 2020 06:04:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:52102 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727995AbgKTLEi (ORCPT ); Fri, 20 Nov 2020 06:04:38 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 7BBF8206E3; Fri, 20 Nov 2020 11:04:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1605870277; bh=YCNIuP+rHY+EGsG+5YueyENgHETlAXHA0lhyzTgpKg4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jF5X2d8Uc+3kwLHcHi8dzwOdSsxKD2S2mEaLOLeH3OL9ppsc9dMe0vCpZnlH/Yju8 ubijW4gZDqpu+JcoZ32zxToUC3RmSSRUcU9rrlmmui2bW6yi6wa/ZMSDgMPcbZoDy1 Uc7MLUA72L8tr7mF2u8+LGbrYwnWN+pcx+HRWjMc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , dja@axtens.net, syzbot+f25ecf4b2982d8c7a640@syzkaller-ppc64.appspotmail.com, Michael Ellerman , Andrew Donnellan Subject: [PATCH 4.9 06/16] powerpc: Fix __clear_user() with KUAP enabled Date: Fri, 20 Nov 2020 12:03:11 +0100 Message-Id: <20201120104540.037227689@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201120104539.706905067@linuxfoundation.org> References: <20201120104539.706905067@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrew Donnellan commit 61e3acd8c693a14fc69b824cb5b08d02cb90a6e7 upstream. The KUAP implementation adds calls in clear_user() to enable and disable access to userspace memory. However, it doesn't add these to __clear_user(), which is used in the ptrace regset code. As there's only one direct user of __clear_user() (the regset code), and the time taken to set the AMR for KUAP purposes is going to dominate the cost of a quick access_ok(), there's not much point having a separate path. Rename __clear_user() to __arch_clear_user(), and make __clear_user() just call clear_user(). Reported-by: syzbot+f25ecf4b2982d8c7a640@syzkaller-ppc64.appspotmail.com Reported-by: Daniel Axtens Suggested-by: Michael Ellerman Fixes: de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection") Signed-off-by: Andrew Donnellan [mpe: Use __arch_clear_user() for the asm version like arm64 & nds32] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191209132221.15328-1-ajd@linux.ibm.com Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/uaccess.h | 9 +++++++-- arch/powerpc/lib/string.S | 4 ++-- arch/powerpc/lib/string_64.S | 6 +++--- 3 files changed, 12 insertions(+), 7 deletions(-) --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -460,7 +460,7 @@ static inline unsigned long __copy_to_us return __copy_to_user_inatomic(to, from, size); } -extern unsigned long __clear_user(void __user *addr, unsigned long size); +unsigned long __arch_clear_user(void __user *addr, unsigned long size); static inline unsigned long clear_user(void __user *addr, unsigned long size) { @@ -468,12 +468,17 @@ static inline unsigned long clear_user(v might_fault(); if (likely(access_ok(VERIFY_WRITE, addr, size))) { allow_write_to_user(addr, size); - ret = __clear_user(addr, size); + ret = __arch_clear_user(addr, size); prevent_write_to_user(addr, size); } return ret; } +static inline unsigned long __clear_user(void __user *addr, unsigned long size) +{ + return clear_user(addr, size); +} + extern long strncpy_from_user(char *dst, const char __user *src, long count); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *str, long n); --- a/arch/powerpc/lib/string.S +++ b/arch/powerpc/lib/string.S @@ -89,7 +89,7 @@ _GLOBAL(memchr) EXPORT_SYMBOL(memchr) #ifdef CONFIG_PPC32 -_GLOBAL(__clear_user) +_GLOBAL(__arch_clear_user) addi r6,r3,-4 li r3,0 li r5,0 @@ -130,5 +130,5 @@ _GLOBAL(__clear_user) PPC_LONG 1b,91b PPC_LONG 8b,92b .text -EXPORT_SYMBOL(__clear_user) +EXPORT_SYMBOL(__arch_clear_user) #endif --- a/arch/powerpc/lib/string_64.S +++ b/arch/powerpc/lib/string_64.S @@ -28,7 +28,7 @@ PPC64_CACHES: .section ".text" /** - * __clear_user: - Zero a block of memory in user space, with less checking. + * __arch_clear_user: - Zero a block of memory in user space, with less checking. * @to: Destination address, in user space. * @n: Number of bytes to zero. * @@ -78,7 +78,7 @@ err3; stb r0,0(r3) mr r3,r4 blr -_GLOBAL_TOC(__clear_user) +_GLOBAL_TOC(__arch_clear_user) cmpdi r4,32 neg r6,r3 li r0,0 @@ -201,4 +201,4 @@ err1; dcbz 0,r3 cmpdi r4,32 blt .Lshort_clear b .Lmedium_clear -EXPORT_SYMBOL(__clear_user) +EXPORT_SYMBOL(__arch_clear_user)