CVE-2022-48874

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

misc: fastrpc: Fix use-after-free and race in fastrpc_map_find

Currently, there is a race window between the point when the mutex is

unlocked in fastrpc_map_lookup and the reference count increasing

(fastrpc_map_get) in fastrpc_map_find, which can also lead to

use-after-free.

So lets merge fastrpc_map_find into fastrpc_map_lookup which allows us

to both protect the maps list by also taking the &fl->lock spinlock and

the reference count, since the spinlock will be released only after.

Add take_ref argument to make this suitable for all callers.