From: Roman Gushchin guro@fb.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@fb.com Cc: Alexei Starovoitov ast@kernel.org Cc: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Sasha Levin alexander.levin@microsoft.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; }