linux-kernel - [PATCH 5.8 143/148] efi/x86: Mark kernel rodata non-executable for mixed mode

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Message-Id: <20200824082420.872500412@linuxfoundation.org>
Date:   Mon, 24 Aug 2020 10:30:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Arvind Sankar <nivedita@...m.mit.edu>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH 5.8 143/148] efi/x86: Mark kernel rodata non-executable for mixed mode

From: Arvind Sankar <nivedita@...m.mit.edu>

commit c8502eb2d43b6b9b1dc382299a4d37031be63876 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/platform/efi/efi_64.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -268,6 +268,8 @@ int __init efi_setup_page_tables(unsigne
 	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;