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 7BCC2C433EF for ; Wed, 15 Jun 2022 01:49:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344029AbiFOBtZ (ORCPT ); Tue, 14 Jun 2022 21:49:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232340AbiFOBtW (ORCPT ); Tue, 14 Jun 2022 21:49:22 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AE1748322 for ; Tue, 14 Jun 2022 18:49:20 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.54]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LN7Th546Zz1K9xF; Wed, 15 Jun 2022 09:47:20 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 15 Jun 2022 09:49:17 +0800 Received: from huawei.com (10.67.174.169) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 15 Jun 2022 09:49:16 +0800 From: Chen Lifu To: , , , , , , , , CC: Subject: [PATCH -next] riscv: lib: uaccess: fix CSR_STATUS SR_SUM bit Date: Wed, 15 Jun 2022 09:47:14 +0800 Message-ID: <20220615014714.1650349-1-chenlifu@huawei.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.67.174.169] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since commit 5d8544e2d007 ("RISC-V: Generic library routines and assembly") and commit ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code"), if __clear_user and __copy_user return from an fixup branch, CSR_STATUS SR_SUM bit will be set, it is a vulnerability, so that S-mode memory accesses to pages that are accessible by U-mode will success. Disable S-mode access to U-mode memory should clear SR_SUM bit. Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") Fixes: ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code") Signed-off-by: Chen Lifu --- arch/riscv/lib/uaccess.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index 8c475f4da308..ec486e5369d9 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -173,11 +173,11 @@ ENTRY(__asm_copy_from_user) ret /* Exception fixup code */ 10: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, t5 ret ENDPROC(__asm_copy_to_user) ENDPROC(__asm_copy_from_user) EXPORT_SYMBOL(__asm_copy_to_user) @@ -225,10 +225,10 @@ ENTRY(__clear_user) j 3b /* Exception fixup code */ 11: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, a1 ret ENDPROC(__clear_user) EXPORT_SYMBOL(__clear_user) -- 2.35.1