From 1707eb843f0d169e029d5b35778467a8a8b5b3fd Mon Sep 17 00:00:00 2001

From: Matthew Garrett <matthew.garrett@nebula.com>

Date: Fri, 9 Mar 2012 08:39:37 -0500

Subject: [PATCH] ACPI: Limit access to custom_method

custom_method effectively allows arbitrary access to system memory, making

it possible for an attacker to circumvent restrictions on module loading.

Disable it if any such restrictions have been enabled.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

---

 drivers/acpi/custom_method.c | 3 +++

 1 file changed, 3 insertions(+)

diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c

index c68e72414a67..4277938af700 100644

--- a/drivers/acpi/custom_method.c

+++ b/drivers/acpi/custom_method.c

@@ -29,6 +29,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,

 	struct acpi_table_header table;

 	acpi_status status;

+	if (secure_modules())

+		return -EPERM;

+

 	if (!(*ppos)) {

 		/* parse the table header to get the table length */

 		if (count <= sizeof(struct acpi_table_header))

-- 

1.9.3