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Message-Id: <20220923173142.805896-2-namhyung@kernel.org>
Date: Fri, 23 Sep 2022 10:31:39 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
linux-perf-users@...r.kernel.org,
Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 1/4] perf record: Fix a segfault in record__read_lost_samples()
When it fails to open events record__open() returns without setting the
session->evlist. Then it gets a segfault in the function trying to read
lost sample counts. You can easily reproduce it as a normal user like:
$ perf record -p 1 true
...
perf: Segmentation fault
...
Skip the function if it has no evlist. And add more protection for evsels
which are not properly initialized.
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/builtin-record.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 741e763436ca..f4f1619199e5 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1888,6 +1888,10 @@ static void record__read_lost_samples(struct record *rec)
struct perf_record_lost_samples *lost;
struct evsel *evsel;
+ /* there was an error during record__open */
+ if (session->evlist == NULL)
+ return;
+
lost = zalloc(PERF_SAMPLE_MAX_SIZE);
if (lost == NULL) {
pr_debug("Memory allocation failed\n");
@@ -1899,6 +1903,8 @@ static void record__read_lost_samples(struct record *rec)
evlist__for_each_entry(session->evlist, evsel) {
struct xyarray *xy = evsel->core.sample_id;
+ if (xy == NULL || evsel->core.fd == NULL)
+ continue;
if (xyarray__max_x(evsel->core.fd) != xyarray__max_x(xy) ||
xyarray__max_y(evsel->core.fd) != xyarray__max_y(xy)) {
pr_debug("Unmatched FD vs. sample ID: skip reading LOST count\n");
--
2.37.3.998.g577e59143f-goog
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