ACPI / util: cast data to u64 before shifting to fix sign extension

obj->buffer.pointer[i] should be cast to u64 to prevent an unintentional
sign extension.  For example, if pointer[7] is 0x80, then the value
0xffffffffff000000 is or'd into mask rather than the intended value
0xff00000000000000

Detected with static analysis by CoverityScan

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index f12a724..050673f 100644 (file)
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -692,7 +692,7 @@ bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
                mask = obj->integer.value;
        else if (obj->type == ACPI_TYPE_BUFFER)
                for (i = 0; i < obj->buffer.length && i < 8; i++)
-                       mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
+                       mask |= (((u64)obj->buffer.pointer[i]) << (i * 8));
        ACPI_FREE(obj);
 
        /*