Re: [PATCH 3/3] perf, stat: Fix free memory access / memory leaks in metrics

[Jiri Olsa <jolsa@redhat.com>]

On Mon, Sep 23, 2019 at 04:33:39PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> 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.
> 
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
>  tools/perf/util/stat-shadow.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 70c87fdb2a43..2c41d47f6f83 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/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);

hum, shouldn't u instead use strdup(name) instead of name?

jirka

>  	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;
>  
> -- 
> 2.21.0
>