[PATCH 6.4 466/800] perf script: Fix allocation of evsel->priv related to per-event dump files

Greg Kroah-Hartman
2023-07-16T20:14:39Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit 36d3e4138e1b6cc9ab179f3f397b5548f8b1eaae ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/builtin-script.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index c57be48d65bb0..2ecfca0fccda0 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2422,6 +2422,9 @@ static int process_sample_event(struct perf_tool *tool,
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)
{
@@ -2430,7 +2433,6 @@ 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)
@@ -2440,14 +2442,13 @@ 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;
}
}

@@ -2753,7 +2754,6 @@ static int perf_script__fopen_per_event_dump(struct perf_script *script)
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);
--
2.39.2