perf script: Fix allocation of evsel->priv related to per-event dump files

When printing output we may want to generate per event files, where the
--per-event-dump option should be used, creating perf.data.EVENT.dump
files instead of printing to stdout.

The callback thar processes event thus expects that evsel->priv->fp
should point to either the per-event FILE descriptor or to stdout.

The a3af66f51bd0bca7 ("perf script: Fix crash because of missing
evsel->priv") changeset fixed a case where evsel->priv wasn't setup,
thus set to NULL, causing a segfault when trying to access
evsel->priv->fp.

But it did it for the non --per-event-dump case by allocating a 'struct
perf_evsel_script' just to set its ->fp to stdout.

Since evsel->priv is only freed when --per-event-dump is used, we ended
up with a memory leak, detected using ASAN.

Fix it by using the same method as perf_script__setup_per_event_dump(),
and reuse that static 'struct perf_evsel_script'.

Also check if evsel_script__new() failed.

Fixes: a3af66f51bd0bca7 ("perf script: Fix crash because of missing evsel->priv")
Reported-by: Ian Rogers <irogers@google.com>
Tested-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: https://lore.kernel.org/lkml/ZH+F0wGAWV14zvMP@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 70549fc..b02ad38 100644 (file)
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2410,6 +2410,9 @@ out_put:
        return ret;
 }
 
+// Used when scr->per_event_dump is not set
+static struct evsel_script es_stdout;
+
 static int process_attr(struct perf_tool *tool, union perf_event *event,
                        struct evlist **pevlist)
 {
@@ -2418,7 +2421,6 @@ static int process_attr(struct perf_tool *tool, union perf_event *event,
        struct evsel *evsel, *pos;
        u64 sample_type;
        int err;
-       static struct evsel_script *es;
 
        err = perf_event__process_attr(tool, event, pevlist);
        if (err)
@@ -2428,14 +2430,13 @@ static int process_attr(struct perf_tool *tool, union perf_event *event,
        evsel = evlist__last(*pevlist);
 
        if (!evsel->priv) {
-               if (scr->per_event_dump) {
+               if (scr->per_event_dump) { 
                        evsel->priv = evsel_script__new(evsel, scr->session->data);
-               } else {
-                       es = zalloc(sizeof(*es));
-                       if (!es)
+                       if (!evsel->priv)
                                return -ENOMEM;
-                       es->fp = stdout;
-                       evsel->priv = es;
+               } else { // Replicate what is done in perf_script__setup_per_event_dump()
+                       es_stdout.fp = stdout;
+                       evsel->priv = &es_stdout;
                }
        }
 
@@ -2741,7 +2742,6 @@ out_err_fclose:
 static int perf_script__setup_per_event_dump(struct perf_script *script)
 {
        struct evsel *evsel;
-       static struct evsel_script es_stdout;
 
        if (script->per_event_dump)
                return perf_script__fopen_per_event_dump(script);