[pptp-server] System Crash with PoPToP!

[Jim Morris]

Hi all.  This is a new one on me.  I just installed PoPToP 1.0.0, from
the binary RPM file available on moretonbay.com, on a new server, after
having successfully run PoPToP (various versions) for months on another
system.

This morning, when testing PoPToP using a Windows 98 client, the server
system crashed hard.  It eventually rebooted, apparently because of the
Linux software watchdog timer.  The last log messages prior to the
reboot
seem to indicate the use of a NULL pointer in the pptpctrl process. 
Here
are the pertinent log messages, reformatted to fit:

----------- begin syslog messages -------------
11:20:01 pptpd[21002]: CTRL: Client 216.78.168.62 control connection 
         started
11:20:01 pptpd[21002]: CTRL: Starting call (launching pppd, opening GRE)
11:20:01 pppd[21003]: pppd 2.3.7 started by root, uid 0
11:20:01 pppd[21003]: Using interface ppp0
11:20:01 pppd[21003]: Connect: ppp0 <--> /dev/pts/1
11:20:01 pppd[21003]: CHAP peer authentication succeeded for jim
11:20:02 pppd[21003]: found interface eth1 for proxy arp
11:20:02 pppd[21003]: local  IP address 192.168.100.230
11:20:02 pppd[21003]: remote IP address 192.168.100.240
11:20:02 pppd[21003]: CCP terminated by peer
11:20:02 pppd[21003]: Compression disabled by peer.
11:22:19 kernel: Unable to handle kernel NULL pointer dereference at
         virtual address 00000070
11:22:19 kernel: current->tss.cr3 = 02745000,
         %cr3 = 02745000
11:22:19 kernel: *pde = 00000000
11:22:19 kernel: Oops: 0002
11:22:19 kernel: CPU:    0
11:22:19 kernel: EIP:    0010:[<d088f21e>]
11:22:19 kernel: EFLAGS: 00010282
11:22:19 kernel: eax: 00002000   ebx: 0000004d
         ecx: c7bad400 edx: 00000000
11:22:19 kernel: esi: c7bad701   edi: c7bad448
         ebp: c7bad448 esp: ce67feb8
11:22:19 kernel: ds: 0018   es: 0018   ss: 0018
11:22:19 kernel: Process pptpctrl (pid: 21002, process nr: 82,
         stackpage=ce67f000)
11:22:19 kernel: Stack: c71e4000 00000000 ffff4d94 00000006
         c7bad448 00000000 cac71800 c7bad72e
11:22:19 kernel:        0000059f d088eef4 c7bad400 c7bad400
         c71e4000 ccd4a000 ce67ff8c d088eb0b
11:22:19 kernel:        c7bad400 c71e4000 ccd4a000 c01aaa52
         c71e4000 00000000 00000000 c01a11aa
11:22:19 kernel: Call Trace: [<d088eef4>] [<d088eb0b>]
         [pty_unthrottle+38/72] [check_unthrottle+42/48]
         [read_chan+1510/1792] [tty_read+176/208]
         [sys_read+194/232]
11:22:19 kernel:        [system_call+52/56] [startup_32+43/164]
11:22:19 kernel: Code: f0 ff 4a 70 0f 94 c0 84 c0 74 09 52 e8 01
         2d 8c ef 83 c4 04
11:37:38 syslogd 1.3-3: restart.
----------- end syslog stuff -------------

Pertinent system information:

- SMP (2 Celeron 433's)
- Redhat 6.0, with latest updates.
- Linux kernel 2.2.14
- PPTP Masquerading kernel module patch installed (ip_masq_pptp)
- pppd 2.3.7 (from Redhat 6.0 CD)
- pptpd 1.0.0, from RPM file on moretonbay.com

Client:  Windows 98

Any advice would be appreciated.  This system is the Samba server
for about 20 people - so I cannot afford for it to reboot
unexpectedly! ;-)

Jim Morris (Jim at Morris.net)