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 1A0DAC43334 for ; Fri, 22 Jul 2022 09:29:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236571AbiGVJ3D (ORCPT ); Fri, 22 Jul 2022 05:29:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236408AbiGVJ2m (ORCPT ); Fri, 22 Jul 2022 05:28:42 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60948B8518; Fri, 22 Jul 2022 02:17:57 -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 ams.source.kernel.org (Postfix) with ESMTPS id 615D0B827BC; Fri, 22 Jul 2022 09:17:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D68E8C341C6; Fri, 22 Jul 2022 09:17:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658481474; bh=ht/zw+tJsdLI5zMA2BjnKf2FhyrjDAtiyH10+522ZUY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HmIsOq2UDgVoiYBTC9lDUegSCL4HNQtQTwOtizc5NozOxtlXxzMrEwrCSH/Adri1p WUJcyBQCuSdcCXiN2mHZm2bmfv6TXFtHEWTSYw/2yJkogAVDMQDS7Qlq0y2SxNe/HS Cf9m+vWtMdphvyo2yxvycxUUz91G5LSCMmvqWezc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , Thadeu Lima de Souza Cascardo , "Peter Zijlstra (Intel)" , Borislav Petkov , Josh Poimboeuf , Linus Torvalds Subject: [PATCH 5.15 82/89] efi/x86: use naked RET on mixed mode call wrapper Date: Fri, 22 Jul 2022 11:11:56 +0200 Message-Id: <20220722091137.929354267@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220722091133.320803732@linuxfoundation.org> References: <20220722091133.320803732@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thadeu Lima de Souza Cascardo commit 51a6fa0732d6be6a44e0032752ad2ac10d67c796 upstream. When running with return thunks enabled under 32-bit EFI, the system crashes with: kernel tried to execute NX-protected page - exploit attempt? (uid: 0) BUG: unable to handle page fault for address: 000000005bc02900 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0011) - permissions violation PGD 18f7063 P4D 18f7063 PUD 18ff063 PMD 190e063 PTE 800000005bc02063 Oops: 0011 [#1] PREEMPT SMP PTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc6+ #166 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:0x5bc02900 Code: Unable to access opcode bytes at RIP 0x5bc028d6. RSP: 0018:ffffffffb3203e10 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000048 RDX: 000000000190dfac RSI: 0000000000001710 RDI: 000000007eae823b RBP: ffffffffb3203e70 R08: 0000000001970000 R09: ffffffffb3203e28 R10: 747563657865206c R11: 6c6977203a696665 R12: 0000000000001710 R13: 0000000000000030 R14: 0000000001970000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8e013ca00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 0000000080050033 CR2: 000000005bc02900 CR3: 0000000001930000 CR4: 00000000000006f0 Call Trace: ? efi_set_virtual_address_map+0x9c/0x175 efi_enter_virtual_mode+0x4a6/0x53e start_kernel+0x67c/0x71e x86_64_start_reservations+0x24/0x2a x86_64_start_kernel+0xe9/0xf4 secondary_startup_64_no_verify+0xe5/0xeb That's because it cannot jump to the return thunk from the 32-bit code. Using a naked RET and marking it as safe allows the system to proceed booting. Fixes: aa3d480315ba ("x86: Use return-thunk in asm code") Reported-by: Guenter Roeck Signed-off-by: Thadeu Lima de Souza Cascardo Cc: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: Josh Poimboeuf Cc: Tested-by: Guenter Roeck Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/x86/platform/efi/efi_thunk_64.S | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/x86/platform/efi/efi_thunk_64.S +++ b/arch/x86/platform/efi/efi_thunk_64.S @@ -22,6 +22,7 @@ #include #include #include +#include .text .code64 @@ -63,7 +64,9 @@ SYM_CODE_START(__efi64_thunk) 1: movq 24(%rsp), %rsp pop %rbx pop %rbp - RET + ANNOTATE_UNRET_SAFE + ret + int3 .code32 2: pushl $__KERNEL_CS