efi_loader: add missing validation of timestamp

The UEFI specification requires that when UEFI variables are set using time
based authentication we have to check that unused fields of the timestamp
are zero

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 74a9c65..f9a0efd 100644 (file)
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -481,11 +481,15 @@ static efi_status_t efi_variable_authenticate(u16 *variable,
        if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
                goto err;
 
+       memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
+       if (timestamp.pad1 || timestamp.nanosecond || timestamp.timezone ||
+           timestamp.daylight || timestamp.pad2)
+               goto err;
+
        *data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
        *data_size -= (sizeof(auth->time_stamp)
                                + auth->auth_info.hdr.dwLength);
 
-       memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
        memset(&tm, 0, sizeof(tm));
        tm.tm_year = timestamp.year;
        tm.tm_mon = timestamp.month;