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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51529C2BB3F for ; Wed, 15 Nov 2023 20:58:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344574AbjKOU6q (ORCPT ); Wed, 15 Nov 2023 15:58:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344702AbjKOU5o (ORCPT ); Wed, 15 Nov 2023 15:57:44 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0293519A9 for ; Wed, 15 Nov 2023 12:57:29 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6B53C433CA; Wed, 15 Nov 2023 20:47:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700081224; bh=+oYMtUJbcZApFFLXOm3x+u/sRxhg09sNA6WAAc2UBAc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LCk4wj7A0ipYU7bUjY0Q759TSSJoP+7D7huui9RduFNQ/zykgIc2UUUw4lXL5yYeF XSdLrDbbEyYoxOvBHQ4sNv5PDYiXgZMzo3TQD9Y2bbRvR+DuRsMWW2TMHRQd6sMJ6G FTn56Mcxa87uFhXVGS6Ap4nYXoTjwjvQn/zdvpT0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dave Hansen , Adam Dunlap , Ingo Molnar , Jacob Xu , Sasha Levin Subject: [PATCH 5.15 009/244] x86/sev-es: Allow copy_from_kernel_nofault() in earlier boot Date: Wed, 15 Nov 2023 15:33:21 -0500 Message-ID: <20231115203548.933364739@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115203548.387164783@linuxfoundation.org> References: <20231115203548.387164783@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adam Dunlap [ Upstream commit f79936545fb122856bd78b189d3c7ee59928c751 ] Previously, if copy_from_kernel_nofault() was called before boot_cpu_data.x86_virt_bits was set up, then it would trigger undefined behavior due to a shift by 64. This ended up causing boot failures in the latest version of ubuntu2204 in the gcp project when using SEV-SNP. Specifically, this function is called during an early #VC handler which is triggered by a CPUID to check if NX is implemented. Fixes: 1aa9aa8ee517 ("x86/sev-es: Setup GHCB-based boot #VC handler") Suggested-by: Dave Hansen Signed-off-by: Adam Dunlap Signed-off-by: Ingo Molnar Tested-by: Jacob Xu Link: https://lore.kernel.org/r/20230912002703.3924521-2-acdunlap@google.com Signed-off-by: Sasha Levin --- arch/x86/mm/maccess.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c index 5a53c2cc169cc..6993f026adec9 100644 --- a/arch/x86/mm/maccess.c +++ b/arch/x86/mm/maccess.c @@ -9,12 +9,21 @@ bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) unsigned long vaddr = (unsigned long)unsafe_src; /* - * Range covering the highest possible canonical userspace address - * as well as non-canonical address range. For the canonical range - * we also need to include the userspace guard page. + * Do not allow userspace addresses. This disallows + * normal userspace and the userspace guard page: */ - return vaddr >= TASK_SIZE_MAX + PAGE_SIZE && - __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); + if (vaddr < TASK_SIZE_MAX + PAGE_SIZE) + return false; + + /* + * Allow everything during early boot before 'x86_virt_bits' + * is initialized. Needed for instruction decoding in early + * exception handlers. + */ + if (!boot_cpu_data.x86_virt_bits) + return true; + + return __is_canonical_address(vaddr, boot_cpu_data.x86_virt_bits); } #else bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) -- 2.42.0