From patchwork Fri Nov 20 11:03:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 329902 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 BF879C64E69 for ; Fri, 20 Nov 2020 11:04:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FA272240C for ; Fri, 20 Nov 2020 11:04:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uN6H6JZE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727401AbgKTLDd (ORCPT ); Fri, 20 Nov 2020 06:03:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:50708 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725789AbgKTLDc (ORCPT ); Fri, 20 Nov 2020 06:03:32 -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 2AAD52222F; Fri, 20 Nov 2020 11:03:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1605870211; bh=qjPwQyoO1sivJ/OQeQhF7DOYuY0uN2zl82LFqxeiZ5g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uN6H6JZEto2duZbVF1cUH4+dQGnIWsC7gMzvuCkye4dRIE2BvXKT3waBCK1jLrQJv KVnrtJbiSbOfQgp7l84CTd/HDYtxTJYlDm2Tiveawy1Y0UznLdqiG7qACILrjqlDFl 7/8/hSpvOTHv1UNaGwlGtiE3UYGTh284D2GQiA3g= 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 4.4 06/15] powerpc: Fix __clear_user() with KUAP enabled Date: Fri, 20 Nov 2020 12:03:04 +0100 Message-Id: <20201120104539.864061299@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201120104539.534424264@linuxfoundation.org> References: <20201120104539.534424264@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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/kernel/ppc_ksyms.c | 3 +++ arch/powerpc/lib/string.S | 2 +- arch/powerpc/lib/string_64.S | 4 ++-- 4 files changed, 13 insertions(+), 5 deletions(-) --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -471,7 +471,7 @@ 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) { @@ -479,12 +479,17 @@ 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/kernel/ppc_ksyms.c +++ b/arch/powerpc/kernel/ppc_ksyms.c @@ -5,6 +5,7 @@ #include #include #include +#include EXPORT_SYMBOL(flush_dcache_range); EXPORT_SYMBOL(flush_icache_range); @@ -43,3 +44,5 @@ EXPORT_SYMBOL(epapr_hypercall_start); #endif EXPORT_SYMBOL(current_stack_pointer); + +EXPORT_SYMBOL(__arch_clear_user); --- a/arch/powerpc/lib/string.S +++ b/arch/powerpc/lib/string.S @@ -122,7 +122,7 @@ _GLOBAL(memchr) blr #ifdef CONFIG_PPC32 -_GLOBAL(__clear_user) +_GLOBAL(__arch_clear_user) addi r6,r3,-4 li r3,0 li r5,0 --- a/arch/powerpc/lib/string_64.S +++ b/arch/powerpc/lib/string_64.S @@ -27,7 +27,7 @@ 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. * @@ -77,7 +77,7 @@ 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