Re: [PATCH v1 08/11] perf session: Smatch: Fix potential NULL pointer dereference

Arnaldo Carvalho de Melo
2019-07-03T19:02:43Z

Em Tue, Jul 02, 2019 at 06:34:17PM +0800, Leo Yan escreveu:
> Based on the following report from Smatch, fix the potential
> NULL pointer dereference check.
>
> tools/perf/util/session.c:1252
> dump_read() error: we previously assumed 'evsel' could be null
> (see line 1249)
>
> tools/perf/util/session.c
> 1240 static void dump_read(struct perf_evsel *evsel, union perf_event *event)
> 1241 {
> 1242 struct read_event *read_event = &event->read;
> 1243 u64 read_format;
> 1244
> 1245 if (!dump_trace)
> 1246 return;
> 1247
> 1248 printf(": %d %d %s %" PRIu64 "\n", event->read.pid, event->read.tid,
> 1249 evsel ? perf_evsel__name(evsel) : "FAIL",
> 1250 event->read.value);
> 1251
> 1252 read_format = evsel->attr.read_format;
> ^^^^^^^
>
> 'evsel' could be NULL pointer, for this case this patch directly bails
> out without dumping read_event.

So this needs another hunk, adding it.

diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 8e0e06d3edfc..f4591a1438b4 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -224,7 +224,7 @@ static int perf_event__repipe_sample(struct perf_tool *tool,
struct perf_evsel *evsel,
struct machine *machine)
{
- if (evsel->handler) {
+ if (evsel && evsel->handler) {
inject_handler f = evsel->handler;
return f(tool, event, sample, evsel, machine);
}

> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
> tools/perf/util/session.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 54cf163347f7..2e61dd6a3574 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1249,6 +1249,9 @@ static void dump_read(struct perf_evsel *evsel, union perf_event *event)
> evsel ? perf_evsel__name(evsel) : "FAIL",
> event->read.value);
>
> + if (!evsel)
> + return;
> +
> read_format = evsel->attr.read_format;
>
> if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
> --
> 2.17.1

--

- Arnaldo