The RTEMS and Linux JFFS2 compression support have a slightly different
interface. This fixes a bug introduced by:
commit 17c3d536ca
Author: Yang Yang <yang.yang29@zte.com.cn>
Date: Thu Jan 28 02:55:35 2021 -0800
jffs2: check the validity of dstlen in jffs2_zlib_compress()
KASAN reports a BUG when download file in jffs2 filesystem.It is
because when dstlen == 1, cpage_out will write array out of bounds.
Actually, data will not be compressed in jffs2_zlib_compress() if
data's length less than 4.
2ea03be47c