Fixed in FEC crash when a large number of dropped packets occur causi… (

#892) * Fixed in FEC crash when a large number of dropped packets occur causing celloff to become negative and therefore accessing out of bounds for rcv.cells deque. This crash can be reproduced by putting Clumsy.exe (Dropped packet / latency simulator) between two machines and turning on lag (200ms will do it) and then turning it off, this causes a consistent crash of SRT.
Haivision · Sep 30, 2019 · c39b88a · c39b88a
1 parent 84b56ca
commit c39b88a
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/srtcore/fec.cpp b/srtcore/fec.cpp
@@ -696,7 +696,7 @@ bool FECFilterBuiltin::receive(const CPacket& rpkt, loss_seqs_t& loss_seqs)
         // be simultaneously also retransmitted. This may confuse the tables.
         int celloff = CSeqNo::seqoff(rcv.cell_base, rpkt.getSeqNo());
         bool past = celloff < 0;
-        bool exists = celloff < int(rcv.cells.size()) && rcv.cells[celloff];
+        bool exists = celloff < int(rcv.cells.size()) && !past && rcv.cells[celloff];
 
         if (past || exists)
         {