[PATCH 5.4 107/155] bpf: Fix cgroup ref leak in cgroup_bpf_inherit on out-of-memory

Greg Kroah-Hartman
2020-03-31T09:18:33Z

From: Andrii Nakryiko <andriin@fb.com>

commit 1d8006abaab4cb90f81add86e8d1bf9411add05a 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: e10360f815ca ("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>

---
kernel/bpf/cgroup.c | 3 +++
1 file changed, 3 insertions(+)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -228,6 +228,9 @@ cleanup:
for (i = 0; i < NR; i++)
bpf_prog_array_free(arrays[i]);

+ for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
+ cgroup_bpf_put(p);
+
percpu_ref_exit(&cgrp->bpf.refcnt);

return -ENOMEM;