/usr/lib/gcc-cross/arm-linux-gnueabihf/5/libasan.so is in libgcc-5-dev-armhf-cross 5.5.0-12ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/arm-linux-gnueabihf/5/../../../../arm-linux-gnueabihf/lib/libasan.so.2