txt/verify.c: fix miscalculated offset to extended data elements

Signed-off-by: Krystian Hebel <krystian.hebel@3mdeb.com>

grub-core/loader/i386/txt/verify.c

@@ -244,9 +244,7 @@ grub_txt_verify_platform (void)
                  N_("TXT heap is not configured correctly"));
 
   bios_size = grub_txt_bios_data_size (txt_heap);
-  /* We support versions >= 4, but bios_data->mle_flags is in versions >= 5. */
-  if ( bios_size < sizeof (grub_uint64_t) + sizeof (*bios_data) -
-                   sizeof (bios_data->mle_flags) ||
+  if ( bios_size < sizeof (grub_uint64_t) + sizeof (*bios_data) ||
        bios_size > heap_size )
      return grub_error (GRUB_ERR_OUT_OF_RANGE,
                  N_("invalid size of the TXT heap BIOS data table"));
@@ -264,16 +262,15 @@ grub_txt_verify_platform (void)
                  bios_data->num_logical_procs);
 
   /*
-   * grub_uint32_t mle_flags is available in versions >= 5, version 4 doesn't
-   * have it. However, the minimal size of extended data element is 8 bytes, so
-   * the size check below is still valid for version 4.
+   * grub_uint32_t mle_flags is supposed to be added in version 5, however, the
+   * only ACM in 630744_003 package that is version 4 (Sandy Bridge & Ivy Bridge
+   * SNB_IVB_SINIT_20190708_PW.bin) seems to also have this field, or at least
+   * a placeholder for it.
    */
   if ( bios_data->version >= 4 && bios_size > sizeof(*bios_data) + sizeof(bios_size) )
     {
       elts = (struct grub_txt_heap_ext_data_element *) ((grub_uint8_t *)bios_data +
-                                                        sizeof(*bios_data) -
-                                                        ( bios_data->version == 4 ?
-                                                          sizeof(bios_data->mle_flags) : 0 ));
+                                                        sizeof(*bios_data));
       err = verify_ext_data_elts(elts, bios_size - sizeof(*bios_data));
     }