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Commit 3960f4fd authored by Roman Gushchin's avatar Roman Gushchin Committed by Daniel Borkmann
Browse files

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: 324bda9e ("bpf: multi program support for cgroup+bpf")
Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent d29ab6e1

kernel/bpf/cgroup.c

+3 −4
Original line number Original line Diff line number Diff line
@@ -95,7 +95,7 @@ static int compute_effective_progs(struct cgroup *cgrp, 
				   enum bpf_attach_type type,

				   enum bpf_attach_type type,

				   struct bpf_prog_array __rcu **array)

				   struct bpf_prog_array __rcu **array)

{

{

	struct bpf_prog_array __rcu *progs;

	struct bpf_prog_array *progs;

	struct bpf_prog_list *pl;

	struct bpf_prog_list *pl;

	struct cgroup *p = cgrp;

	struct cgroup *p = cgrp;

	int cnt = 0;

	int cnt = 0;
@@ -120,13 +120,12 @@ static int compute_effective_progs(struct cgroup *cgrp, 
					    &p->bpf.progs[type], node) {

					    &p->bpf.progs[type], node) {

				if (!pl->prog)

				if (!pl->prog)

					continue;

					continue;

				rcu_dereference_protected(progs, 1)->

				progs->progs[cnt++] = pl->prog;

					progs[cnt++] = pl->prog;

			}

			}

		p = cgroup_parent(p);

		p = cgroup_parent(p);

	} while (p);

	} while (p);





	*array = progs;

	rcu_assign_pointer(*array, progs);

	return 0;

	return 0;

}

}