From: Matthew Garrett <mj...@srcf.ucam.org> 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 <mj...@srcf.ucam.org> Signed-off-by: David Howells <dhowe...@redhat.com> cc: linux-a...@vger.kernel.org Signed-off-by: Matthew Garrett <matthewgarr...@google.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 4451877f83b6..ac8a90dc7096 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("ACPI custom methods")) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) -- 2.21.0.392.gf8f6787159e-goog