Merge tag 'trace-v5.16-5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "Update to tracing histogram variable string copy

  A fix to only copy the size of the field to the histogram string did
  not take into account that the size can be larger than the storage"

* tag 'trace-v5.16-5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Add length protection to histogram string copies

include/linux/trace_events.h

@@ -673,7 +673,7 @@ struct trace_event_file {
 
 #define PERF_MAX_TRACE_SIZE	8192
 
-#define MAX_FILTER_STR_VAL	256	/* Should handle KSYM_SYMBOL_LEN */
+#define MAX_FILTER_STR_VAL	256U	/* Should handle KSYM_SYMBOL_LEN */
 
 enum event_trigger_type {
 	ETT_NONE		= (0),

kernel/trace/trace_events_hist.c

@@ -3026,8 +3026,10 @@ static inline void __update_field_vars(struct tracing_map_elt *elt,
 		if (val->flags & HIST_FIELD_FL_STRING) {
 			char *str = elt_data->field_var_str[j++];
 			char *val_str = (char *)(uintptr_t)var_val;
+			unsigned int size;
 
-			strscpy(str, val_str, val->size);
+			size = min(val->size, STR_VAR_LEN_MAX);
+			strscpy(str, val_str, size);
 			var_val = (u64)(uintptr_t)str;
 		}
 		tracing_map_set_var(elt, var_idx, var_val);
@@ -4914,6 +4916,7 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 			if (hist_field->flags & HIST_FIELD_FL_STRING) {
 				unsigned int str_start, var_str_idx, idx;
 				char *str, *val_str;
+				unsigned int size;
 
 				str_start = hist_data->n_field_var_str +
 					hist_data->n_save_var_str;
@@ -4922,7 +4925,9 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 
 				str = elt_data->field_var_str[idx];
 				val_str = (char *)(uintptr_t)hist_val;
-				strscpy(str, val_str, hist_field->size);
+
+				size = min(hist_field->size, STR_VAR_LEN_MAX);
+				strscpy(str, val_str, size);
 
 				hist_val = (u64)(uintptr_t)str;
 			}