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bpf: fix rcu annotations in compute_effective_progs() 

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: 324bda9e6c ("bpf: multi program support for cgroup+bpf")
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Roman Gushchin 2018-07-13 12:41:11 -07:00 committed by Daniel Borkmann
parent d29ab6e1fa
commit 3960f4fd65
1 changed files with 3 additions and 4 deletions
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7
kernel/bpf/cgroup.c
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@ -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;
}