netdev - [PATCH bpf] bpf: fix cgroup ref leak in cgroup_bpf

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Message-ID: <20200309224017.1063297-1-andriin@fb.com>
Date:   Mon, 9 Mar 2020 15:40:17 -0700
From:   Andrii Nakryiko <andriin@...com>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
        <daniel@...earbox.net>, <guro@...com>
CC:     <andrii.nakryiko@...il.com>, <kernel-team@...com>,
        Andrii Nakryiko <andriin@...com>
Subject: [PATCH bpf] bpf: fix cgroup ref leak in cgroup_bpf_inherit on out-of-memory

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

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 9a500fadbef5..5220a67392fc 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -227,6 +227,9 @@ int cgroup_bpf_inherit(struct cgroup *cgrp)
 	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;
-- 
2.17.1