Debian: CVE-2022-50042: linux -- security update

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

net: genl: fix error path memory leak in policy dumping

If construction of the array of policies fails when recording
non-first policy we need to unwind.

netlink_policy_dump_add_policy() itself also needs fixing as
it currently gives up on error without recording the allocated
pointer in the pstate pointer.