Validate size of EFI GUID partition entries.

commit fa039d5f upstream.

Otherwise corrupted EFI partition tables can cause total confusion.
Signed-off-by: Timo Warns <warns@pre-sense.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/partitions/efi.c

@@ -349,6 +349,12 @@ is_gpt_valid(struct block_device *bdev, u64 lba,
 		goto fail;
 	}
 
+	/* Check that sizeof_partition_entry has the correct value */
+	if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
+		pr_debug("GUID Partitition Entry Size check failed.\n");
+		goto fail;
+	}
+
 	if (!(*ptes = alloc_read_gpt_entries(bdev, *gpt)))
 		goto fail;