bpf: Check bloom filter map value size

In the Linux kernel, the following vulnerability has been resolved: bpf: Check bloom filter map value size This patch adds a missing check to bloom filter creating, rejecting values above KMALLOC_MAX_SIZE. This brings the bloom map in line with many other map types. The lack of this protection can cause kernel crashes for value sizes that overflow int's. Such a crash was caught by syzkaller. The next patch adds more guard-rails at a lower level.