On 5/15/15 12:15 PM, Alexei Starovoitov wrote:
there is a race between perf_event_free_bpf_prog() and free_trace_kprobe():__free_event() event->destroy(event) tp_perf_event_destroy() perf_trace_destroy() perf_trace_event_unreg() which is dropping event->tp_event->perf_refcount and allows to proceed in: unregister_trace_kprobe() unregister_kprobe_event() trace_remove_event_call() probe_remove_event_call() free_trace_kprobe() while __free_event does: call_rcu(&event->rcu_head, free_event_rcu); free_event_rcu() perf_event_free_bpf_prog() To fix the race simply move perf_event_free_bpf_prog() before event->destroy(), since event->tp_event is still valid at that point. Note, perf_trace_destroy() is not racing with trace_remove_event_call() since they both grab event_mutex. Fixes: 2541517c32be ("tracing, perf: Implement BPF programs attached to kprobes") Reported-by: Wang Nan <wangn...@huawei.com> Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
ping. This is needed in 4.1. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
