[12/16] ACPI: Limit access to custom_method when the kernel is locked down
diff mbox

Message ID 147933292359.19316.8799773007176633243.stgit@warthog.procyon.org.uk
State New
Headers show

Commit Message

David Howells Nov. 16, 2016, 9:48 p.m. UTC
From: Matthew Garrett <matthew.garrett@nebula.com>

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>
---

 drivers/acpi/custom_method.c |    3 +++
 1 file changed, 3 insertions(+)


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Patch
diff mbox

diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index c68e72414a67..e4d721c330c0 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 (kernel_is_locked_down())
+		return -EPERM;
+
 	if (!(*ppos)) {
 		/* parse the table header to get the table length */
 		if (count <= sizeof(struct acpi_table_header))