From c333ace27a3115f2b56f25987bdb7ef05f71836c Mon Sep 17 00:00:00 2001
From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Wed, 5 Apr 2017 17:40:30 +0100
Subject: [PATCH 54/62] ACPI: Limit access to custom_method when the kernel is
locked down
Patch-mainline: No, submitted
References: fate#314486
custom_method effectively allows arbitrary access to system memory, making
it possible for an attacker to circumvent restrictions on module loading.
Disable it if the kernel is locked down.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
drivers/acpi/custom_method.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *fil
struct acpi_table_header table;
acpi_status status;
+ if (kernel_is_locked_down())
+ return -EPERM;
+
if (!(*ppos)) {
/* parse the table header to get the table length */
if (count <= sizeof(struct acpi_table_header))