In the Linux kernel, the following vulnerability has been resolved: tracing/hist: Fix out-of-bound write on 'action_data.var_ref_idx' When generate a synthetic event with many params and then create a trace action for it [1], kernel panic happened [2]. It is because that in trace_action_create() 'data->n_params' is up to SYNTH_FIELDS_MAX (current value is 64), and array 'data->var_ref_idx' keeps indices into array 'hist_data->var_refs' for each synthetic event param, but the length of 'data->var_ref_idx' is TRACING_MAP_VARS_MAX (current value is 16), so out-of-bound write happened when 'data->n_params' more than 16. In this case, 'data->match_data.event' is overwritten and eventually cause the panic. To solve the issue, adjust the length of 'data->var_ref_idx' to be SYNTH_FIELDS_MAX an