From 11f6a65fe2ea62a4d5d0e08ded3b4917b2ee8fea Mon Sep 17 00:00:00 2001
From: Juliusz Chroboczek <jch@irif.fr>
Date: Sun, 20 Jun 2021 19:52:21 +0200
Subject: [PATCH] Avoid crash in samplebuilder.PopWithTimestamp

If sample is null, PopWithTimestamp will crash with SIGSEGV.
---
 pkg/media/samplebuilder/samplebuilder.go      | 3 +++
 pkg/media/samplebuilder/samplebuilder_test.go | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/pkg/media/samplebuilder/samplebuilder.go b/pkg/media/samplebuilder/samplebuilder.go
index 69f059f7..ac330396 100644
--- a/pkg/media/samplebuilder/samplebuilder.go
+++ b/pkg/media/samplebuilder/samplebuilder.go
@@ -300,6 +300,9 @@ func (s *SampleBuilder) Pop() *media.Sample {
 // no sample is compiled).
 func (s *SampleBuilder) PopWithTimestamp() (*media.Sample, uint32) {
 	sample := s.Pop()
+	if sample == nil {
+		return nil, 0
+	}
 	return sample, sample.PacketTimestamp
 }
 
diff --git a/pkg/media/samplebuilder/samplebuilder_test.go b/pkg/media/samplebuilder/samplebuilder_test.go
index ea2498d1..a5a918a5 100644
--- a/pkg/media/samplebuilder/samplebuilder_test.go
+++ b/pkg/media/samplebuilder/samplebuilder_test.go
@@ -379,3 +379,12 @@ func TestSampleBuilderWithPacketReleaseHandler(t *testing.T) {
 		t.Errorf("Unexpected packet released by samples built")
 	}
 }
+
+func TestPopWithTimestamp(t *testing.T) {
+	t.Run("Crash on nil", func(t *testing.T) {
+		s := New(0, &fakeDepacketizer{}, 1)
+		sample, timestamp := s.PopWithTimestamp()
+		assert.Nil(t, sample)
+		assert.Equal(t, uint32(0), timestamp)
+	})
+}