From c8c088ba0edf65044c254b96fc438c91914aaab0 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 30 Nov 2017 13:47:54 -0800 Subject: [PATCH] bpf: set maximum number of attached progs to 64 for a single perf tp cgropu+bpf prog array has a maximum number of 64 programs. Let us apply the same limit here. Fixes: e87c6bc3852b ("bpf: permit multiple bpf attachments for a single perf event") Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann --- kernel/bpf/core.c | 3 ++- kernel/trace/bpf_trace.c | 8 ++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index b9f8686a84cf..86b50aa26ee8 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1447,7 +1447,8 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu *progs) rcu_read_lock(); prog = rcu_dereference(progs)->progs; for (; *prog; prog++) - cnt++; + if (*prog != &dummy_bpf_prog.prog) + cnt++; rcu_read_unlock(); return cnt; } diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 27d1f4ffa3de..0ce99c379c30 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -759,6 +759,8 @@ const struct bpf_prog_ops perf_event_prog_ops = { static DEFINE_MUTEX(bpf_event_mutex); +#define BPF_TRACE_MAX_PROGS 64 + int perf_event_attach_bpf_prog(struct perf_event *event, struct bpf_prog *prog) { @@ -772,6 +774,12 @@ int perf_event_attach_bpf_prog(struct perf_event *event, goto unlock; old_array = event->tp_event->prog_array; + if (old_array && + bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) { + ret = -E2BIG; + goto unlock; + } + ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array); if (ret < 0) goto unlock;