From patchwork Wed May 13 09:45:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 225975 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=-6.9 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 8A127C2D0FD for ; Wed, 13 May 2020 09:58:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6273A24930 for ; Wed, 13 May 2020 09:58:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363883; bh=efmXkP4nZQuabVonmCLtMzWmGLAsXGPDsTiDa8BZylU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ydVtbZjMXePVuK+/757CXG63XYUDSzk6qW3WrStaDpCeGeDBGR00P0Xml4f3Zx84P pkW09Fq8KIxzJgK9pM2/Z0wrxLIFbfkwLpIA14FE/fNDJAaGmyLBPq4WU9o5hits5R kBNLr3Jp32PdP9YoASDLZZ54wUoa3Byq7guFtRIs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387574AbgEMJ5X (ORCPT ); Wed, 13 May 2020 05:57:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:58346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387681AbgEMJzV (ORCPT ); Wed, 13 May 2020 05:55:21 -0400 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 5DA76205ED; Wed, 13 May 2020 09:55:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589363720; bh=efmXkP4nZQuabVonmCLtMzWmGLAsXGPDsTiDa8BZylU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hx1Z5i7YM9LbtnieshT9E8lxfQb2WvlT9wy1qc3dZ0nGgyZ/lpOqG3teF6H5UcSz3 D/y2qC71LrK3cpxA9A9+8yO06QasiJ6780o6ZZ1+0EL8rdLBURZjF6atsE4ZY7cXnB GSS5zB+vJ8ctDTK9WVLLGVJfj5EM1zJbMpPcjXbA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miroslav Benes , Josh Poimboeuf , Ingo Molnar , Andy Lutomirski , Dave Jones , Jann Horn , Peter Zijlstra , Thomas Gleixner , Vince Weaver Subject: [PATCH 5.6 097/118] x86/entry/64: Fix unwind hints in register clearing code Date: Wed, 13 May 2020 11:45:16 +0200 Message-Id: <20200513094425.791714943@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513094417.618129545@linuxfoundation.org> References: <20200513094417.618129545@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Josh Poimboeuf commit 06a9750edcffa808494d56da939085c35904e618 upstream. The PUSH_AND_CLEAR_REGS macro zeroes each register immediately after pushing it. If an NMI or exception hits after a register is cleared, but before the UNWIND_HINT_REGS annotation, the ORC unwinder will wrongly think the previous value of the register was zero. This can confuse the unwinding process and cause it to exit early. Because ORC is simpler than DWARF, there are a limited number of unwind annotation states, so it's not possible to add an individual unwind hint after each push/clear combination. Instead, the register clearing instructions need to be consolidated and moved to after the UNWIND_HINT_REGS annotation. Fixes: 3f01daecd545 ("x86/entry/64: Introduce the PUSH_AND_CLEAN_REGS macro") Reviewed-by: Miroslav Benes Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Andy Lutomirski Cc: Dave Jones Cc: Jann Horn Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vince Weaver Link: https://lore.kernel.org/r/68fd3d0bc92ae2d62ff7879d15d3684217d51f08.1587808742.git.jpoimboe@redhat.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/calling.h | 40 +++++++++++++++++++++------------------- 1 file changed, 21 insertions(+), 19 deletions(-) --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -98,13 +98,6 @@ For 32-bit we have the following convent #define SIZEOF_PTREGS 21*8 .macro PUSH_AND_CLEAR_REGS rdx=%rdx rax=%rax save_ret=0 - /* - * Push registers and sanitize registers of values that a - * speculation attack might otherwise want to exploit. The - * lower registers are likely clobbered well before they - * could be put to use in a speculative execution gadget. - * Interleave XOR with PUSH for better uop scheduling: - */ .if \save_ret pushq %rsi /* pt_regs->si */ movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ @@ -114,34 +107,43 @@ For 32-bit we have the following convent pushq %rsi /* pt_regs->si */ .endif pushq \rdx /* pt_regs->dx */ - xorl %edx, %edx /* nospec dx */ pushq %rcx /* pt_regs->cx */ - xorl %ecx, %ecx /* nospec cx */ pushq \rax /* pt_regs->ax */ pushq %r8 /* pt_regs->r8 */ - xorl %r8d, %r8d /* nospec r8 */ pushq %r9 /* pt_regs->r9 */ - xorl %r9d, %r9d /* nospec r9 */ pushq %r10 /* pt_regs->r10 */ - xorl %r10d, %r10d /* nospec r10 */ pushq %r11 /* pt_regs->r11 */ - xorl %r11d, %r11d /* nospec r11*/ pushq %rbx /* pt_regs->rbx */ - xorl %ebx, %ebx /* nospec rbx*/ pushq %rbp /* pt_regs->rbp */ - xorl %ebp, %ebp /* nospec rbp*/ pushq %r12 /* pt_regs->r12 */ - xorl %r12d, %r12d /* nospec r12*/ pushq %r13 /* pt_regs->r13 */ - xorl %r13d, %r13d /* nospec r13*/ pushq %r14 /* pt_regs->r14 */ - xorl %r14d, %r14d /* nospec r14*/ pushq %r15 /* pt_regs->r15 */ - xorl %r15d, %r15d /* nospec r15*/ UNWIND_HINT_REGS + .if \save_ret pushq %rsi /* return address on top of stack */ .endif + + /* + * Sanitize registers of values that a speculation attack might + * otherwise want to exploit. The lower registers are likely clobbered + * well before they could be put to use in a speculative execution + * gadget. + */ + xorl %edx, %edx /* nospec dx */ + xorl %ecx, %ecx /* nospec cx */ + xorl %r8d, %r8d /* nospec r8 */ + xorl %r9d, %r9d /* nospec r9 */ + xorl %r10d, %r10d /* nospec r10 */ + xorl %r11d, %r11d /* nospec r11 */ + xorl %ebx, %ebx /* nospec rbx */ + xorl %ebp, %ebp /* nospec rbp */ + xorl %r12d, %r12d /* nospec r12 */ + xorl %r13d, %r13d /* nospec r13 */ + xorl %r14d, %r14d /* nospec r14 */ + xorl %r15d, %r15d /* nospec r15 */ + .endm .macro POP_REGS pop_rdi=1 skip_r11rcx=0