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Message-ID: <20180915012944.179481-7-alexander.levin@microsoft.com>
Date: Sat, 15 Sep 2018 01:29:53 +0000
From: Sasha Levin <Alexander.Levin@...rosoft.com>
To: "stable@...r.kernel.org" <stable@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Roman Gushchin <guro@...com>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 07/92] bpf: fix rcu annotations in
compute_effective_progs()
From: Roman Gushchin <guro@...com>
[ Upstream commit 3960f4fd6585608e8cc285d9665821985494e147 ]
The progs local variable in compute_effective_progs() is marked
as __rcu, which is not correct. This is a local pointer, which
is initialized by bpf_prog_array_alloc(), which also now
returns a generic non-rcu pointer.
The real rcu-protected pointer is *array (array is a pointer
to an RCU-protected pointer), so the assignment should be performed
using rcu_assign_pointer().
Fixes: 324bda9e6c5a ("bpf: multi program support for cgroup+bpf")
Signed-off-by: Roman Gushchin <guro@...com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
kernel/bpf/cgroup.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 3d83ee7df381..badabb0b435c 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -95,7 +95,7 @@ static int compute_effective_progs(struct cgroup *cgrp,
enum bpf_attach_type type,
struct bpf_prog_array __rcu **array)
{
- struct bpf_prog_array __rcu *progs;
+ struct bpf_prog_array *progs;
struct bpf_prog_list *pl;
struct cgroup *p = cgrp;
int cnt = 0;
@@ -120,13 +120,12 @@ static int compute_effective_progs(struct cgroup *cgrp,
&p->bpf.progs[type], node) {
if (!pl->prog)
continue;
- rcu_dereference_protected(progs, 1)->
- progs[cnt++] = pl->prog;
+ progs->progs[cnt++] = pl->prog;
}
p = cgroup_parent(p);
} while (p);
- *array = progs;
+ rcu_assign_pointer(*array, progs);
return 0;
}
--
2.17.1
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