If the blocksize is corrupted and has a lace, you may have a buffer overflow. Should fix #5658.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 61d512e93967a2b8e8ac6212de9f6c2db94bcc69)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>