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 2E154C7EE26 for ; Mon, 8 May 2023 09:51:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233795AbjEHJvX (ORCPT ); Mon, 8 May 2023 05:51:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233434AbjEHJvL (ORCPT ); Mon, 8 May 2023 05:51:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FA3623A2E for ; Mon, 8 May 2023 02:50:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 12B5F621BB for ; Mon, 8 May 2023 09:50:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 209CBC433EF; Mon, 8 May 2023 09:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1683539455; bh=1fYRg93c9MiVpQNZIJe92pp2i1LRO2vQkjgDV2j3MHo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W2qlTAfQsLtmxuczMhrTPVJm+WxiAmeAI+iEzqkN6bLgp7n8HM8ozW/424dkLj8A9 JgdL+ZOCrM4vmKEcfgebxFVSGwwPE5Hvx8GSNxxnAEy2u3Db+9+oMNE7p0a3kPNQ6V OMhQ3edU261I94oYtZ+DF2vjrpO1r8QfctiTtm8s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ard Biesheuvel , Mark Rutland , Kees Cook , Catalin Marinas Subject: [PATCH 6.1 022/611] arm64: Always load shadow stack pointer directly from the task struct Date: Mon, 8 May 2023 11:37:44 +0200 Message-Id: <20230508094422.442651627@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508094421.513073170@linuxfoundation.org> References: <20230508094421.513073170@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ard Biesheuvel commit 2198d07c509f1db4a1185d1f65aaada794c6ea59 upstream. All occurrences of the scs_load macro load the value of the shadow call stack pointer from the task which is current at that point. So instead of taking a task struct register argument in the scs_load macro to specify the task struct to load from, let's always reference the current task directly. This should make it much harder to exploit any instruction sequences reloading the shadow call stack pointer register from memory. Signed-off-by: Ard Biesheuvel Acked-by: Mark Rutland Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230109174800.3286265-2-ardb@kernel.org Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/scs.h | 7 ++++--- arch/arm64/kernel/entry.S | 4 ++-- arch/arm64/kernel/head.S | 2 +- 3 files changed, 7 insertions(+), 6 deletions(-) --- a/arch/arm64/include/asm/scs.h +++ b/arch/arm64/include/asm/scs.h @@ -9,15 +9,16 @@ #ifdef CONFIG_SHADOW_CALL_STACK scs_sp .req x18 - .macro scs_load tsk - ldr scs_sp, [\tsk, #TSK_TI_SCS_SP] + .macro scs_load_current + get_current_task scs_sp + ldr scs_sp, [scs_sp, #TSK_TI_SCS_SP] .endm .macro scs_save tsk str scs_sp, [\tsk, #TSK_TI_SCS_SP] .endm #else - .macro scs_load tsk + .macro scs_load_current .endm .macro scs_save tsk --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -272,7 +272,7 @@ alternative_if ARM64_HAS_ADDRESS_AUTH alternative_else_nop_endif 1: - scs_load tsk + scs_load_current .else add x21, sp, #PT_REGS_SIZE get_current_task tsk @@ -845,7 +845,7 @@ SYM_FUNC_START(cpu_switch_to) msr sp_el0, x1 ptrauth_keys_install_kernel x1, x8, x9, x10 scs_save x0 - scs_load x1 + scs_load_current ret SYM_FUNC_END(cpu_switch_to) NOKPROBE(cpu_switch_to) --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -404,7 +404,7 @@ SYM_FUNC_END(create_kernel_mapping) stp xzr, xzr, [sp, #S_STACKFRAME] add x29, sp, #S_STACKFRAME - scs_load \tsk + scs_load_current adr_l \tmp1, __per_cpu_offset ldr w\tmp2, [\tsk, #TSK_TI_CPU]