ACPI: Make sure the FADT is at least rev 2 before using the reset register

The reset register was only introduced with version 2 of the FADT, so we
should check that the FADT revision before trusting its contents.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
index 4870aaaa2ae1..a6c77e8b37bd 100644
--- a/drivers/acpi/reboot.c
+++ b/drivers/acpi/reboot.c
@@ -15,6 +15,11 @@ void acpi_reboot(void)
 
         rr = &acpi_gbl_FADT.reset_register;
 
+        /* ACPI reset register was only introduced with v2 of the FADT */
+
+        if (acpi_gbl_FADT.header.revision < 2)
+                return;
+
         /* Is the reset register supported? The spec says we should be
          * checking the bit width and bit offset, but Windows ignores
          * these fields */