Fixed busy loop in case of partially malformed rtcp packet

BUG=webrtc:5574

Review URL: https://codereview.webrtc.org/1726573003

Cr-Commit-Position: refs/heads/master@{#11946}
diff --git a/webrtc/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
index 252b482..c43bb0e 100644
--- a/webrtc/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtcp_receiver_unittest.cc
@@ -157,6 +157,13 @@
   EXPECT_EQ(0U, rtcp_packet_info_.rtcpPacketTypeFlags);
 }
 
+TEST_F(RtcpReceiverTest, InvalidFeedbackPacketIsIgnored) {
+  // Too short feedback packet.
+  const uint8_t bad_packet[] = {0x80, RTCPUtility::PT_RTPFB, 0, 0};
+  EXPECT_EQ(0, InjectRtcpPacket(bad_packet, sizeof(bad_packet)));
+  EXPECT_EQ(0U, rtcp_packet_info_.rtcpPacketTypeFlags);
+}
+
 TEST_F(RtcpReceiverTest, InjectSrPacket) {
   const uint32_t kSenderSsrc = 0x10203;
   rtcp::SenderReport sr;