panic: bad TCP data offset 24 (tlen 22)

Matthew Dillon dillon at
Tue Mar 22 11:27:27 PST 2005

    Hello Joe.  Jeff and I have been looking at it.  It looks like your
    panic occured after a fragmented packet got reassembled.

    Are you running any special protocols, like IPSEC or anything like

    If you have a kernel core still around we may need it to help diagnose
    the problem.

					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>

:My box crashed today with the following panic:
:panic: bad TCP data offset 24 (tlen 22)
:I was experiencing some packet loss just prior to the crash.  I was
:running nmap on my access points IP address and stepped away for a
:minute.  When I returned Xorg was frozen, no keyboard or mouse
:response then the machine rebooted.
:$uname -a
:DragonFly <hostname> 1.1-Stable DragonFly 1.1-Stable #7: Mon Mar 14
:11:24:00 EST 2005     root@<hostname>:/usr/obj/usr/src/sys/SOL i386
:panic messages:
:panic: bad TCP data offset 24 (tlen 22)
:(kgdb) bt
:#0  dumpsys () at /usr/src/sys/kern/kern_shutdown.c:508
:#1  0xc01abee7 in boot (howto=256) at
:#2  0xc01ac318 in panic (fmt=0xc036aee0 "bad TCP data offset %d (tlen
:    at /usr/src/sys/kern/kern_shutdown.c:620
:#3  0xc0213dbd in tcp_input (m=0xc28c3200)
:    at /usr/src/sys/netinet/tcp_input.c:635
:#4  0xc020f181 in transport_processing_oncpu (m=0xc28c3200, hlen=20, 
:    ip=0xded5100e, nexthop=0x0) at /usr/src/sys/netinet/ip_input.c:423
:#5  0xc020fa90 in ip_input (m=0xc28c3200)
:    at /usr/src/sys/netinet/ip_input.c:1112
:#6  0xc020f1df in ip_input_handler (msg0=0xc2749300)
:    at /usr/src/sys/netinet/ip_input.c:454
:#7  0xc0218502 in tcpmsg_service_loop (dummy=0x0)
:    at /usr/src/sys/netinet/tcp_subr.c:391
:#8  0xc01b0f84 in lwkt_create () at /usr/src/sys/kern/lwkt_thread.c:1260
:Let me know if more info is needed.

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