panic: bad TCP data offset 24 (tlen 22)

Joe Talbott josepht at
Mon Mar 21 14:38:35 PST 2005

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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