You can try to use other methods to backdoor the linux. (not driver)
~/Projects/kernelbuild/linux-5.0.3 ➭ zcat /proc/config.gz > .config
~/Projects/kernelbuild/linux-5.0.3 ➭ ll drivers/backdoor
total 12K
-rw-r--r-- 1 debug debug 3.3K Mar 22 16:41 backdoor.c
-rw-r--r-- 1 debug debug 94 Mar 22 16:57 Kconfig
-rw-r--r-- 1 debug debug 37 Mar 22 17:01 Makefile
~/Projects/kernelbuild/linux-5.0.3 ➭ make
...
AR drivers/backdoor/built-in.a
...
~/Projects/kernelbuild/linux-5.0.3 ➭ ll drivers/backdoor
total 16K
-rw-r--r-- 1 debug debug 3.3K Mar 22 16:41 backdoor.c
-rw-r--r-- 1 debug debug 8 Mar 22 17:23 built-in.a
-rw-r--r-- 1 debug debug 94 Mar 22 16:57 Kconfig
-rw-r--r-- 1 debug debug 37 Mar 22 17:01 Makefile
-rw-r--r-- 1 debug debug 0 Mar 22 17:23 modules.order
~/Projects/kernelbuild/linux-5.0.3 ➭ cat drivers/backdoor/Makefile
obj-$(CONFIG_BACKDOOR) += backdoor.o
~/Projects/kernelbuild/linux-5.0.3 ➭ cat drivers/backdoor/Kconfig
config BACKDOOR
tristate "backdoor module"
# depends on ARM
help
this is a backdoor module
add a backdoor driver into kernel-source
You can try to use other methods to backdoor the linux. (not driver)
create a iso
If you are a archer, archiso is a good choice.
references