linux-kernel - [tip: efi/urgent] efi/x86: Mark kernel rodata non-executable for mixed mode

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Message-ID: <159810354148.3192.13677289427486753048.tip-bot2@tip-bot2>
Date:   Sat, 22 Aug 2020 13:39:01 -0000
From:   "tip-bot2 for Arvind Sankar" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     <stable@...r.kernel.org>, Arvind Sankar <nivedita@...m.mit.edu>,
        Ard Biesheuvel <ardb@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: efi/urgent] efi/x86: Mark kernel rodata non-executable for mixed mode

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     c8502eb2d43b6b9b1dc382299a4d37031be63876
Gitweb:        https://git.kernel.org/tip/c8502eb2d43b6b9b1dc382299a4d37031be63876
Author:        Arvind Sankar <nivedita@...m.mit.edu>
AuthorDate:    Fri, 17 Jul 2020 15:45:26 -04:00
Committer:     Ard Biesheuvel <ardb@...nel.org>
CommitterDate: Thu, 20 Aug 2020 11:18:36 +02:00

efi/x86: Mark kernel rodata non-executable for mixed mode

When remapping the kernel rodata section RO in the EFI pagetables, the
protection flags that were used for the text section are being reused,
but the rodata section should not be marked executable.

Cc: <stable@...r.kernel.org>
Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
Link: https://lore.kernel.org/r/20200717194526.3452089-1-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/platform/efi/efi_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 413583f..6af4da1 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -259,6 +259,8 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
 	npages = (__end_rodata - __start_rodata) >> PAGE_SHIFT;
 	rodata = __pa(__start_rodata);
 	pfn = rodata >> PAGE_SHIFT;
+
+	pf = _PAGE_NX | _PAGE_ENC;
 	if (kernel_map_pages_in_pgd(pgd, pfn, rodata, npages, pf)) {
 		pr_err("Failed to map kernel rodata 1:1\n");
 		return 1;