[PATCH bpf-next] bpf: fix flags check in bpf_percpu_cgroup_storage_update()

[Roman Gushchin <guro@fb.com>]

Fix an issue in bpf_percpu_cgroup_storage_update(): it should return
-EINVAL on an attempt to pass BPF_NOEXIST rather than BPF_EXIST.

Cgroup local storage is automatically created on attaching of a bpf
program to a cgroup, and it can't be done from the userspace.

Fixes: 0daef9b42374 ("bpf: introduce per-cpu cgroup local storage")
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
---
 kernel/bpf/local_storage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index c739f6dcc3c2..190535f6d5e2 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -191,7 +191,7 @@ int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *_key,
 	int cpu, off = 0;
 	u32 size;
 
-	if (unlikely(map_flags & BPF_EXIST))
+	if (map_flags & BPF_NOEXIST)
 		return -EINVAL;
 
 	rcu_read_lock();
-- 
2.17.1