Date: Mon, 05 Apr 2021 09:03:36 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 254725] [tcp] 13.0-RC4 crash tcp_lro Message-ID: <bug-254725-7501-AUqeQV8LSC@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-254725-7501@https.bugs.freebsd.org/bugzilla/> References: <bug-254725-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D254725 Richard Scheffenegger <rscheff@freebsd.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|13.0-RC4 crash tcp_lro |[tcp] 13.0-RC4 crash | |tcp_lro --- Comment #14 from Richard Scheffenegger <rscheff@freebsd.org> --- Extracted a more complete set of packet headers belonging to the problematic session from the privately provided core. The session is ECN-enabled At the time of the panic, SENTFIN was set Based on the Timestamp option of the incoming ACKs, serious reordering and spurious retransmissions were going on. The final packet with FIN originally has a payload of 1 byte. (TSopt val ..5625), but that is apparently lost and not received by the client. Susequently (based on TSopt val), just the FIN is retransmitted twice, with TSopt val ..5861 and ..5979 (e.g. when a transmission opportunity would be there, but no new data is available). The RTT appears to be nearly 100ms from the very last round, sRTT is averag= ed at 275ms At the panic, TSval would have been ..5988 This is for retransmitting the final payload byte, as the client only SACKed the 1st FIN retransmission.=20 However, for some reason that byte is no longer available in the send socket buffer, causing the crash. Srv -> clnt F. 9999:10000(1) //dropped Clnt -> Srv E. 1:1(0) ack -26seg <sack -25seg:9999> (unobserved retransmission Srv->Clnt) Clnt -> Srv E. 1:1(0) ack 9999 Srv -> cnt F. 10000:10000(0) Clnt -> Srv E. 1:1(0) ack 9999 <sack 10000:10001> attempt to retransmit 10000:10001(1) -> crash. However, current attempts to recreate this misbehavior were unsuccessful in recreating the panic. --=20 You are receiving this mail because: You are the assignee for the bug.=
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