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Bug #4646

closed

TCP reassembly, failed assert app_progress > last_ack_abs, both sides need to be pruned

Added by Jeff Lucovsky over 1 year ago. Updated 7 months ago.

Status:
Closed
Priority:
Normal
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Target version:
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Description

Found by oss-fuzz
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=35626

Minimized reproducer with suricata is
./src/suricata -r lolb.pcap -k none -c suricata.yaml --set stream.midstream=true

What happens is
- first packet (midstream) all ok (ack = 1)
- second packet, from the other side, ack is ok, but sequence indicates a gap from first packet ack (seq = 77)
- third packet, sequence ok, ack is increased since first packet confirming the gap (ack = 77) StreamTcpUpdateAppLayerProgress is called by AppLayerHandleTCPData at the end of if (flags & STREAM_GAP) {
- Fourth packet is in first direction (seq and ack meaningless)

At the end of third packet, the 76 gap does not get subtracted in app_progress_rel as StreamTcpPruneSession only considers the other stream


Files

lolb.pcap (984 Bytes) lolb.pcap Philippe Antoine, 06/30/2021 07:26 PM

Related issues 1 (0 open1 closed)

Copied from Bug #4549: TCP reassembly, failed assert app_progress > last_ack_abs, both sides need to be prunedClosedVictor JulienActions
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