On Wed, 1 Apr 2026 19:22:24 +0800
Pengpeng Hou <[email protected]> wrote:
> diff --git a/kernel/trace/trace_events_hist.c
> b/kernel/trace/trace_events_hist.c
> index f9c8a4f078ea..4172c91605af 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -2966,12 +2966,16 @@ find_synthetic_field_var(struct hist_trigger_data
> *target_hist_data,
> struct hist_field *event_var;
> char *synthetic_name;
>
> + if ((sizeof("synthetic_") - 1) + strlen(field_name) >=
> + MAX_FILTER_STR_VAL)
> + return ERR_PTR(-E2BIG);
> +
> synthetic_name = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
> if (!synthetic_name)
> return ERR_PTR(-ENOMEM);
>
> - strcpy(synthetic_name, "synthetic_");
> - strcat(synthetic_name, field_name);
> + scnprintf(synthetic_name, MAX_FILTER_STR_VAL, "synthetic_%s",
> + field_name);
>
> event_var = find_event_var(target_hist_data, system, event_name,
> synthetic_name);
>
> @@ -3018,6 +3022,8 @@ create_field_var_hist(struct hist_trigger_data
> *target_hist_data,
> struct hist_field *event_var;
> char *saved_filter;
> char *cmd;
> + size_t cmdlen;
> + size_t off;
> int ret;
>
> if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX) {
> @@ -3048,13 +3054,36 @@ create_field_var_hist(struct hist_trigger_data
> *target_hist_data,
> /* See if a synthetic field variable has already been created */
> event_var = find_synthetic_field_var(target_hist_data, subsys_name,
> event_name, field_name);
> - if (!IS_ERR_OR_NULL(event_var))
> + if (IS_ERR(event_var))
> + return event_var;
> + if (event_var)
> return event_var;
>
> var_hist = kzalloc_obj(*var_hist);
> if (!var_hist)
> return ERR_PTR(-ENOMEM);
>
> + saved_filter = find_trigger_filter(hist_data, file);
> +
> + cmdlen = strlen("keys=") + strlen(":synthetic_") +
> + strlen(field_name) + strlen("=") + strlen(field_name);
Instead of doing all this complex updates, let's use seq_buf in this patch
instead. That's what it's for.
I'll take patch 1 as is, just update this patch.
Thanks,
-- Steve
> + first = true;
> + for_each_hist_key_field(i, hist_data) {
> + key_field = hist_data->fields[i];
> + if (!first)
> + cmdlen++;
> + cmdlen += strlen(key_field->field->name);
> + first = false;
> + }
> +
> + if (saved_filter)
> + cmdlen += strlen(" if ") + strlen(saved_filter);
> +
> + if (cmdlen >= MAX_FILTER_STR_VAL) {
> + kfree(var_hist);
> + return ERR_PTR(-E2BIG);
> + }
> +
> cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
> if (!cmd) {
> kfree(var_hist);
> @@ -3062,28 +3091,24 @@ create_field_var_hist(struct hist_trigger_data
> *target_hist_data,
> }
>
> /* Use the same keys as the compatible histogram */
> - strcat(cmd, "keys=");
> + off = scnprintf(cmd, MAX_FILTER_STR_VAL, "keys=");
> + first = true;
>
> for_each_hist_key_field(i, hist_data) {
> key_field = hist_data->fields[i];
> - if (!first)
> - strcat(cmd, ",");
> - strcat(cmd, key_field->field->name);
> + off += scnprintf(cmd + off, MAX_FILTER_STR_VAL - off, "%s%s",
> + first ? "" : ",", key_field->field->name);
> first = false;
> }
>
> /* Create the synthetic field variable specification */
> - strcat(cmd, ":synthetic_");
> - strcat(cmd, field_name);
> - strcat(cmd, "=");
> - strcat(cmd, field_name);
> + off += scnprintf(cmd + off, MAX_FILTER_STR_VAL - off,
> + ":synthetic_%s=%s", field_name, field_name);
>
> /* Use the same filter as the compatible histogram */
> - saved_filter = find_trigger_filter(hist_data, file);
> - if (saved_filter) {
> - strcat(cmd, " if ");
> - strcat(cmd, saved_filter);
> - }
> + if (saved_filter)
> + scnprintf(cmd + off, MAX_FILTER_STR_VAL - off, " if %s",
> + saved_filter);
>
> var_hist->cmd = kstrdup(cmd, GFP_KERNEL);
> if (!var_hist->cmd) {
