On Thu, Oct 19, 2017 at 03:52:19PM +0100, David Howells wrote:
> From: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
I have reviewed this patch. Please feel free to add:
Reviewed-by: "Lee, Chun-Yi" <jlee@xxxxxxxx>
Thanks!
Joey Lee
> cc: linux-acpi@xxxxxxxxxxxxxxx
> ---
>
> 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..b33fba70ec51 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))
>
> --
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