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Subject[PATCH 4/6] perf tools: Pre-check sample size before parsing
Date
Check that the total size of the sample fields having a fixed
size do not exceed the one of the whole event. This robustifies
the sample parsing.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
---
tools/perf/builtin-test.c | 4 +++-
tools/perf/util/event.c | 16 ++++++++++++++++
tools/perf/util/event.h | 12 +++++++++++-
tools/perf/util/evsel.c | 6 +++++-
tools/perf/util/python.c | 5 +++--
tools/perf/util/session.c | 1 +
tools/perf/util/session.h | 2 ++
7 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
index 11e3c84..44d7df2 100644
--- a/tools/perf/builtin-test.c
+++ b/tools/perf/builtin-test.c
@@ -474,6 +474,7 @@ static int test__basic_mmap(void)
unsigned int nr_events[nsyscalls],
expected_nr_events[nsyscalls], i, j;
struct perf_evsel *evsels[nsyscalls], *evsel;
+ int sample_size = perf_sample_size(attr.sample_type);

for (i = 0; i < nsyscalls; ++i) {
char name[64];
@@ -558,7 +559,8 @@ static int test__basic_mmap(void)
goto out_munmap;
}

- perf_event__parse_sample(event, attr.sample_type, false, &sample);
+ perf_event__parse_sample(event, attr.sample_type, sample_size,
+ false, &sample);
evsel = perf_evlist__id2evsel(evlist, sample.id);
if (evsel == NULL) {
pr_debug("event with id %" PRIu64
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 1023f67..17c1c3c 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -35,6 +35,22 @@ const char *perf_event__name(unsigned int id)
return perf_event__names[id];
}

+int perf_sample_size(u64 sample_type)
+{
+ u64 mask = sample_type & PERF_SAMPLE_MASK;
+ int size = 0;
+ int i;
+
+ for (i = 0; i < 64; i++) {
+ if ((mask << i) & 1)
+ size++;
+ }
+
+ size *= sizeof(u64);
+
+ return size;
+}
+
static struct perf_sample synth_sample = {
.pid = -1,
.tid = -1,
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 9c35170..c083328 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -56,6 +56,13 @@ struct read_event {
u64 id;
};

+
+#define PERF_SAMPLE_MASK \
+ (PERF_SAMPLE_IP | PERF_SAMPLE_TID | \
+ PERF_SAMPLE_TIME | PERF_SAMPLE_ADDR | \
+ PERF_SAMPLE_ID | PERF_SAMPLE_STREAM_ID | \
+ PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD)
+
struct sample_event {
struct perf_event_header header;
u64 array[];
@@ -75,6 +82,8 @@ struct perf_sample {
struct ip_callchain *callchain;
};

+int perf_sample_size(u64 sample_type);
+
#define BUILD_ID_SIZE 20

struct build_id_event {
@@ -178,6 +187,7 @@ int perf_event__preprocess_sample(const union perf_event *self,
const char *perf_event__name(unsigned int id);

int perf_event__parse_sample(const union perf_event *event, u64 type,
- bool sample_id_all, struct perf_sample *sample);
+ int sample_size, bool sample_id_all,
+ struct perf_sample *sample);

#endif /* __PERF_RECORD_H */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d6fd59b..bfce8bf 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -304,7 +304,8 @@ static int perf_event__parse_id_sample(const union perf_event *event, u64 type,
}

int perf_event__parse_sample(const union perf_event *event, u64 type,
- bool sample_id_all, struct perf_sample *data)
+ int sample_size, bool sample_id_all,
+ struct perf_sample *data)
{
const u64 *array;

@@ -319,6 +320,9 @@ int perf_event__parse_sample(const union perf_event *event, u64 type,

array = event->sample.array;

+ if (sample_size + sizeof(event->header) > event->header.size)
+ return -EFAULT;
+
if (type & PERF_SAMPLE_IP) {
data->ip = event->ip.ip;
array++;
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 8b0eff8..4174c09 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -690,8 +690,9 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
return PyErr_NoMemory();

first = list_entry(evlist->entries.next, struct perf_evsel, node);
- perf_event__parse_sample(event, first->attr.sample_type, sample_id_all,
- &pevent->sample);
+ perf_event__parse_sample(event, first->attr.sample_type,
+ perf_sample_size(first->attr.sample_type),
+ sample_id_all, &pevent->sample);
return pyevent;
}

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index db65206..8940fd8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -97,6 +97,7 @@ out:
void perf_session__update_sample_type(struct perf_session *self)
{
self->sample_type = perf_evlist__sample_type(self->evlist);
+ self->sample_size = perf_sample_size(self->sample_type);
self->sample_id_all = perf_evlist__sample_id_all(self->evlist);
perf_session__id_header_size(self);
}
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 8daaa2d..66d4e14 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -43,6 +43,7 @@ struct perf_session {
*/
struct hists hists;
u64 sample_type;
+ int sample_size;
int fd;
bool fd_pipe;
bool repipe;
@@ -159,6 +160,7 @@ static inline int perf_session__parse_sample(struct perf_session *session,
struct perf_sample *sample)
{
return perf_event__parse_sample(event, session->sample_type,
+ session->sample_size,
session->sample_id_all, sample);
}

--
1.7.3.2


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