bpf: Fix cgroup ref leak in cgroup_bpf_inherit on out-of-memory

bpf: Fix cgroup ref leak in cgroup_bpf_inherit on out-of-memory

commit a21d13991649759b86b2d871a30e8b8e13a62369 upstream.

There is no compensating cgroup_bpf_put() for each ancestor cgroup in
cgroup_bpf_inherit(). If compute_effective_progs returns error, those cgroups
won't be freed ever. Fix it by putting them in cleanup code path.

Fixes: 1d657688841a ("bpf: cgroup: prevent out-of-order release of cgroup bpf")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20200309224017.1063297-1-andriin@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>