/usr/share/doc/libsfasan0-dbg-armhf-cross is in libsfasan0-dbg-armhf-cross 4.8.5-4ubuntu1cross2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-4.8-arm-linux-gnueabihf-base
/usr/share/doc/gcc-4.8-arm-linux-gnueabihf-base