I would like to thank all the people who responded with ideas & suggestions to my problem. My system has now remained stable the whole day with the offending user logging
in 27 times without a hitch. Confidence is high!
There is a bug somewhere between ipppd and the tcp stack so I am posting this to the isdn4linux people as well, in the interests of ensuring ongoing Linux reliability.
How to cause the oops: Hopefully this is enough to go on. If anyone need more info about my systems, I will be happy to comply (no tel.number/userid/passwd combinations
though :)
================
1. Setup a linux server with an ISDN connection (I use a pair of AVM Fritz!PCI cards)
2. Setup ippp options WITHOUT mentioning ccp or lzs. (sample options file below). Do NOT install the experimental isdn_lzscomp module.
3. Activate pop3 services using ipop3d
4. Have an NT4 box dial in using M$Outlook to start the dial and pick up mail. On the NT side make sure that the "Enable modem error control" and "Enable modem compression"
are ticked.
(Dial-up-Networking --> Edit-Entry-and-modem-properties --> Basic --> Configure -->)
I fixed the oops by simply adding "noccp" and "nolzs" to the options file. This is a workaround, however, and not a fix. The code should either not enable "lzs" by default,
or should cope with the situation better when lzs is enabled and the module is isdn_lzscomp missing! I noticed that the configure scripts enable lzs support if isdn_lzscomp
is in the kernel tree.
=========sample-ppp-options=====
/dev/ippp11
ipcp-accept-local
ipcp-accept-remote
noipdefault
192.168.1.102:192.168.22.102
ms-dns 192.168.1.1 # Linux named service
ms-wins 192.168.22.1 # samba WINS service
-vj
-vjcomp
-ac
-pc
-bsdcomp
+pap
+chap
login
mru 1524
mtu 1500
# Uncomment next 2 lines to avoid oops!
#noccp
#nolzs
============end-of-file=========
=========================================================
Relevant parts of the original e-mail...
>
> 4. Version Information
> 4.1 ipop3d v7.59
> 4.2 isdn drivers (drivers/isdn): isdn-2.2-1999-06-21
> 4.3 isdn utils: isdn4k-utils-3.0beta2
> 4.4 kernel (/proc/version)
> Linux version 2.2.7 (root@amber.mss) (gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)) #9 SMP Thu Jul 8 09:42:50 BST 1999
>
> ********************SYSLOG OUTPUT*********************
> Jul 8 08:45:03 amber ipppd[708]: Check_passwd called with user=tina
> Jul 8 08:45:03 amber ipppd[708]: user tina logged in
> Jul 8 08:45:03 amber ipppd[708]: MPPP negotiation, He: No We: No
> Jul 8 08:45:03 amber ipppd[708]: CCP enabled! Trying CCP.
> Jul 8 08:45:03 amber ipppd[708]: CCP: got ccp-unit 0 for link 0 (protocol: 0x80fd)
> Jul 8 08:45:03 amber ipppd[708]: ccp_resetci!
> Jul 8 08:45:03 amber ipppd[708]: Kernel check for LZS failed
> Jul 8 08:45:03 amber ipppd[708]: local IP address 192.168.1.103
> Jul 8 08:45:03 amber ipppd[708]: remote IP address 192.168.22.103
> Jul 8 08:45:09 amber ipppd[708]: ccp_resetci!
> Jul 8 08:45:09 amber ipppd[708]: Kernel check for LZS failed
> Jul 8 08:45:10 amber kernel: ippp: no decompressor defined!
> Jul 8 08:45:13 amber last message repeated 2 times
> Jul 8 08:45:13 amber kernel: Warning: kfree_skb passed an skb still on a list (from c016d797).
An oops follows here - now you too can create your own :)
>
> ********************END OF SYSLOG OUTPUT************************
>
> =========================================
> 7. Environment
>
> 7.1 ver_linux
> -- Versions installed: (if some fields are empty or looks
> -- unusual then possibly you have very old versions)
> Linux amber.mss 2.2.7 #9 SMP Thu Jul 8 09:42:50 BST 1999 i686 unknown
> Kernel modules 2.1.121
> Gnu C egcs-2.91.66
> Binutils 2.9.1.0.23
> Linux C Library 2.1.1
> Dynamic linker ldd (GNU libc) 2.1.1
> Procps 2.0.2
> Mount 2.9o
> Net-tools 1.51
> Kbd [option...]
> Sh-utils 1.16
> Modules Loaded ip_masq_vdolive ip_masq_raudio ip_masq_quake ip_masq_irc ip_masq_ftp ip_masq_cuseeme hisax isdn slhc tulip aic7xxx
>
> [7.5] ISDN subsystem
> Command to load hisax driver...
> /sbin/modprobe -v hisax id=HiSax1%HiSax2 type=27,27 protocol=2,2
>
> [7.6] /proc/pci
> Isdn cards (from /proc/pci)
> Bus 0, device 17, function 0:
> Network controller: AVM A1 (Fritz) (rev 2).
> Medium devsel. Fast back-to-back capable. IRQ 18.
> Non-prefetchable 32 bit memory at 0xe9002000 [0xe9002000].
> I/O at 0xdc00 [0xdc01].
> Bus 0, device 18, function 0:
> Network controller: AVM A1 (Fritz) (rev 2).
> Medium devsel. Fast back-to-back capable. IRQ 19.
> Non-prefetchable 32 bit memory at 0xe9003000 [0xe9003000].
> I/O at 0xe000 [0xe001].
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