bpf: fix map not being uncharged during map creation failure

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 20b2b24f upstream.

In map_create(), we first find and create the map, then once that
suceeded, we charge it to the user's RLIMIT_MEMLOCK, and then fetch
a new anon fd through anon_inode_getfd(). The problem is, once the
latter fails f.e. due to RLIMIT_NOFILE limit, then we only destruct
the map via map->ops->map_free(), but without uncharging the previously
locked memory first. That means that the user_struct allocation is
leaked as well as the accounted RLIMIT_MEMLOCK memory not released.
Make the label names in the fix consistent with bpf_prog_load().

Fixes: aaac3ba9 ("bpf: charge user for creation of BPF maps and programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

kernel/bpf/syscall.c

@@ -152,7 +152,7 @@ static int map_create(union bpf_attr *attr)
 
 	err = bpf_map_charge_memlock(map);
 	if (err)
-		goto free_map;
+		goto free_map_nouncharge;
 
 	err = bpf_map_new_fd(map);
 	if (err < 0)
@@ -162,6 +162,8 @@ static int map_create(union bpf_attr *attr)
 	return err;
 
 free_map:
+	bpf_map_uncharge_memlock(map);
+free_map_nouncharge:
 	map->ops->map_free(map);
 	return err;
 }