CVE-2022-49875

In the Linux kernel, the following vulnerability has been resolved:

bpftool: Fix NULL pointer dereference when pin {PROG, MAP, LINK} without FILE

When using bpftool to pin {PROG, MAP, LINK} without FILE,
segmentation fault will occur. The reson is that the lack
of FILE will cause strlen to trigger NULL pointer dereference.
The corresponding stacktrace is shown below:

do_pin
do_pin_any
do_pin_fd
mount_bpffs_for_pin
strlen(name) <- NULL pointer dereference

Fix it by adding validation to the common process.