perf stat: Fix free memory access / memory leaks in metrics

Make sure to not free the name passed in by the caller, but free all the
allocated ids when parsing expressions.

The loop at the end knows that the first entry shouldn't be freed, so
make sure the caller name is the first entry.

Fixes

  % perf stat -M IpB,IpCall,IpTB,IPC,Retiring_SMT,Frontend_Bound_SMT,Kernel_Utilization,CPU_Utilization --metric-only -a -I 1000 sleep 2

  valgrind:
       1.009943231 ==21527== Invalid read of size 1
  ==21527==    at 0x483CB74: strcmp (vg_replace_strmem.c:849)
  ==21527==    by 0x582CF8: collect_all_aliases (stat-display.c:554)
  ==21527==    by 0x582EB3: collect_data (stat-display.c:577)
  ==21527==    by 0x583A32: print_counter_aggr (stat-display.c:806)
  ==21527==    by 0x584FAD: perf_evlist__print_counters (stat-display.c:1200)
  ==21527==    by 0x45133A: print_counters (builtin-stat.c:655)
  ==21527==    by 0x450629: process_interval (builtin-stat.c:353)
  ==21527==    by 0x450FBD: __run_perf_stat (builtin-stat.c:564)
  ==21527==    by 0x451285: run_perf_stat (builtin-stat.c:636)
  ==21527==    by 0x454619: cmd_stat (builtin-stat.c:1966)
  ==21527==    by 0x4D557D: run_builtin (perf.c:310)
  ==21527==    by 0x4D57EA: handle_internal_command (perf.c:362)
  ==21527==  Address 0x12826cd0 is 0 bytes inside a block of size 25 free'd
  ==21527==    at 0x4839A0C: free (vg_replace_malloc.c:540)
  ==21527==    by 0x627041: __zfree (zalloc.c:13)
  ==21527==    by 0x57F66A: generic_metric (stat-shadow.c:814)
  ==21527==    by 0x580B21: perf_stat__print_shadow_stats (stat-shadow.c:1057)
  ==21527==    by 0x58418E: print_metric_headers (stat-display.c:943)
  ==21527==    by 0x5844BC: print_interval (stat-display.c:1004)
  ==21527==    by 0x584DEB: perf_evlist__print_counters (stat-display.c:1172)
  ==21527==    by 0x45133A: print_counters (builtin-stat.c:655)
  ==21527==    by 0x450629: process_interval (builtin-stat.c:353)
  ==21527==    by 0x450FBD: __run_perf_stat (builtin-stat.c:564)
  ==21527==    by 0x451285: run_perf_stat (builtin-stat.c:636)
  ==21527==    by 0x454619: cmd_stat (builtin-stat.c:1966)
  ==21527==  Block was alloc'd at
  ==21527==    at 0x483880B: malloc (vg_replace_malloc.c:309)
  ==21527==    by 0x51677DE: strdup (in /usr/lib64/libc-2.29.so)
  ==21527==    by 0x506457: parse_events_name (parse-events.c:1754)
  ==21527==    by 0x5550BB: parse_events_parse (parse-events.y:214)
  ==21527==    by 0x50694D: parse_events__scanner (parse-events.c:1887)
  ==21527==    by 0x506AEF: parse_events (parse-events.c:1927)
  ==21527==    by 0x521D8B: metricgroup__parse_groups (metricgroup.c:527)
  ==21527==    by 0x45156F: parse_metric_groups (builtin-stat.c:721)
  ==21527==    by 0x6228A9: get_value (parse-options.c:243)
  ==21527==    by 0x62363F: parse_short_opt (parse-options.c:348)
  ==21527==    by 0x62363F: parse_options_step (parse-options.c:536)
  ==21527==    by 0x62363F: parse_options_subcommand (parse-options.c:651)
  ==21527==    by 0x453C1D: cmd_stat (builtin-stat.c:1718)
  ==21527==    by 0x4D557D: run_builtin (perf.c:310)

and also a leak report.

Committer testing:

Before:

  # perf stat -M IpB,IpCall,IpTB,IPC,Retiring_SMT,Frontend_Bound_SMT,Kernel_Utilization,CPU_Utilization --metric-only -a -I 1000 sleep 2
  #           time      CPU_Utilization
       1.000470810                      free(): double free detected in tcache 2
  Aborted (core dumped)
  #

After:

  # perf stat -M IpB,IpCall,IpTB,IPC,Retiring_SMT,Frontend_Bound_SMT,Kernel_Utilization,CPU_Utilization --metric-only -a -I 1000 sleep 2
  #           time      CPU_Utilization
       1.000494752                  0.1
       2.001105112                  0.1
  #
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lore.kernel.org/lkml/20190923233339.25326-3-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/stat-shadow.c

@@ -738,6 +738,8 @@ static void generic_metric(struct perf_stat_config *config,
 	char *n, *pn;
 
 	expr__ctx_init(&pctx);
+	/* Must be first id entry */
+	expr__add_id(&pctx, name, avg);
 	for (i = 0; metric_events[i]; i++) {
 		struct saved_value *v;
 		struct stats *stats;
@@ -776,8 +778,6 @@ static void generic_metric(struct perf_stat_config *config,
 			expr__add_id(&pctx, n, avg_stats(stats)*scale);
 	}
 
-	expr__add_id(&pctx, name, avg);
-
 	if (!metric_events[i]) {
 		const char *p = metric_expr;