io/gzio: Add init_dynamic_block() clean up if unpacking codes fails

io/gzio: Add init_dynamic_block() clean up if unpacking codes fails

init_dynamic_block() didn't clean up gzio->tl and td in some error
paths. This left td pointing to part of tl. Then in grub_gzio_close(),
when tl was freed the storage for td would also be freed. The code then
attempts to free td explicitly, performing a UAF and then a double free.

Explicitly clean up tl and td in the error paths.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/081-io-gzio-Add-init_dynamic_block-clean-up-if-unpacking-codes-fails.patch