kern/64250: 5.2.1 kernel panics on ifconfig when kernel has no INET6 stuff

[Ronald F.Guilmette]

>Number:         64250
>Category:       kern
>Synopsis:       5.2.1 kernel panics on ifconfig when kernel has no INET6 stuff
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Mar 14 01:10:11 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Ronald F. Guilmette
>Release:        FreeBSD 5.2.1-RELEASE i386
>Organization:
Infinite Monkeys & Co.
>Environment:
System: FreeBSD segfault.monkeys.com 5.2.1-RELEASE FreeBSD 5.2.1-RELEASE #0: Sat Mar 13 19:19:29 PST 2004 root at segfault.monkeys.com:/usr/src/sys/i386/compile/rfg20040313-4 i386

>Description:

I configured a 5.2.1 kernel, using the config file attached below, and
when I installed that and then rebooted, the kernel started up ok and
started to run processes, but then, when `ifconfig' was executed (as
a result of the various /etc/rc* files) the kernel panic'd with a
page fault.

This was fully reproducable (3 times).

By process of elimination, I determined that the problem was directly
tide to the fact that I can commented out the INET6 option in the
kernel configuration file.  When that option was uncommented again,
the new kernel gen'd from that worked just fine.

>How-To-Repeat:

On an i686 platform, configure a kernel using the config file below, then
build, install, and boot it, and then do an `ifconfig', or else allow one
to be done as part of the normal /etc/rc* startup scripts.

The kernel will panic with a page fault.  The process running at the time
this occurs will always be `ifconfig'.

cut here for kernel config file
------------------------------------------------------------------------
machine		i386
#cpu		I486_CPU
#cpu		I586_CPU
cpu		I686_CPU
ident		"rfg20040313-3"

#To statically compile in device wiring instead of /boot/device.hints
#hints		"GENERIC.hints"		#Default places to look for devices.

#makeoptions	DEBUG=-g		#Build kernel with gdb(1) debug symbols

#options		NMBCLUSTERS=4096
#options		IPFIREWALL
#options		IPFIREWALL_VERBOSE
#options		IPDIVERT
#options		EXT2FS

options 	SCHED_4BSD		#4BSD scheduler
options 	INET			#InterNETworking
#options 	INET6			#IPv6 communications protocols
options 	FFS			#Berkeley Fast Filesystem
options 	SOFTUPDATES		#Enable FFS soft updates support
options 	UFS_ACL			#Support for access control lists
options 	UFS_DIRHASH		#Improve performance on big directories
#options 	MD_ROOT			#MD is a potential root device
options 	NFSCLIENT		#Network Filesystem Client
options 	NFSSERVER		#Network Filesystem Server
#options 	NFS_ROOT		#NFS usable as /, requires NFSCLIENT
options 	MSDOSFS			#MSDOS Filesystem
options 	CD9660			#ISO 9660 Filesystem
options 	PROCFS			#Process filesystem (requires PSEUDOFS)
options 	PSEUDOFS		#Pseudo-filesystem framework
options 	COMPAT_43		#Compatible with BSD 4.3 [KEEP THIS!]
options 	COMPAT_FREEBSD4		#Compatible with FreeBSD4
options 	SCSI_DELAY=5000		#Delay (in ms) before probing SCSI
options 	KTRACE			#ktrace(1) support
options 	SYSVSHM			#SYSV-style shared memory
options 	SYSVMSG			#SYSV-style message queues
options 	SYSVSEM			#SYSV-style semaphores
options 	_KPOSIX_PRIORITY_SCHEDULING #Posix P1003_1B real-time extensions
options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
options 	AHC_REG_PRETTY_PRINT	# Print register bitfields in debug
					# output.  Adds ~128k to driver.
options 	AHD_REG_PRETTY_PRINT	# Print register bitfields in debug
					# output.  Adds ~215k to driver.
options 	PFIL_HOOKS		# pfil(9) framework

# Debugging for use in -current
#options 	DDB			#Enable the kernel debugger
#options 	INVARIANTS		#Enable calls of extra sanity checking
options 	INVARIANT_SUPPORT	#Extra sanity checks of internal structures, required by INVARIANTS
#options 	WITNESS			#Enable checks to detect deadlocks and cycles
#options 	WITNESS_SKIPSPIN	#Don't run witness on spinlocks for speed

# To make an SMP kernel, the next two are needed
#options 	SMP			# Symmetric MultiProcessor Kernel
device		apic			# I/O APIC

device		isa
#device		eisa
device		pci

# Floppy drives
device		fdc

# ATA and ATAPI devices
device		ata
device		atadisk			# ATA disk drives
#device		ataraid			# ATA RAID drives
device		atapicd			# ATAPI CDROM drives
#device		atapifd			# ATAPI floppy drives
#device		atapist			# ATAPI tape drives
options 	ATA_STATIC_ID		#Static device numbering

# SCSI Controllers
#device		ahb		# EISA AHA1742 family
device		ahc		# AHA2940 and onboard AIC7xxx devices
#device		ahd		# AHA39320/29320 and onboard AIC79xx devices
#device		amd		# AMD 53C974 (Tekram DC-390(T))
#device		isp		# Qlogic family
#device		mpt		# LSI-Logic MPT-Fusion
##device		ncr		# NCR/Symbios Logic
#device		sym		# NCR/Symbios Logic (newer chipsets + those of `ncr')
#device		trm		# Tekram DC395U/UW/F DC315U adapters
#
#device		adv		# Advansys SCSI adapters
#device		adw		# Advansys wide SCSI adapters
#device		aha		# Adaptec 154x SCSI adapters
#device		aic		# Adaptec 15[012]x SCSI adapters, AIC-6[23]60.
#device		bt		# Buslogic/Mylex MultiMaster SCSI adapters
#
#device		ncv		# NCR 53C500
#device		nsp		# Workbit Ninja SCSI-3
#device		stg		# TMC 18C30/18C50

# SCSI peripherals
device		scbus		# SCSI bus (required for SCSI)
#device		ch		# SCSI media changers
device		da		# Direct Access (disks)
#device		sa		# Sequential Access (tape etc)
#device		cd		# CD
#device		pass		# Passthrough device (direct SCSI access)
#device		ses		# SCSI Environmental Services (and SAF-TE)

# RAID controllers interfaced to the SCSI subsystem
#device		amr		# AMI MegaRAID
#device		asr		# DPT SmartRAID V, VI and Adaptec SCSI RAID
#device		ciss		# Compaq Smart RAID 5*
#device		dpt		# DPT Smartcache III, IV - See NOTES for options
#device		iir		# Intel Integrated RAID
#device		ips		# IBM (Adaptec) ServeRAID
#device		mly		# Mylex AcceleRAID/eXtremeRAID

# RAID controllers
#device		aac		# Adaptec FSA RAID
#device		aacp		# SCSI passthrough for aac (requires CAM)
#device		ida		# Compaq Smart RAID
#device		mlx		# Mylex DAC960 family
#device		pst		# Promise Supertrak SX6000
#device		twe		# 3ware ATA RAID

# atkbdc0 controls both the keyboard and the PS/2 mouse
device		atkbdc		# AT keyboard controller
device		atkbd		# AT keyboard
device		psm		# PS/2 mouse

device		vga		# VGA video card driver

device		splash		# Splash screen and screen saver support

# syscons is the default console driver, resembling an SCO console
device		sc

# Enable this for the pcvt (VT220 compatible) console driver
#device		vt
#options 	XSERVER			# support for X server on a vt console
#options 	FAT_CURSOR		# start with block cursor

device		agp		# support several AGP chipsets

# Floating point support - do not disable.
device		npx

# Power management support (see NOTES for more options)
#device		apm
# Add suspend/resume support for the i8254.
device		pmtimer

# PCCARD (PCMCIA) support
# Pcmcia and cardbus bridge support
#device		cbb			# cardbus (yenta) bridge
#device		pcic			# ExCA ISA and PCI bridges
#device		pccard			# PC Card (16-bit) bus
#device		cardbus			# CardBus (32-bit) bus

# Serial (COM) ports
device		sio		# 8250, 16[45]50 based serial ports

# Parallel port
device		ppc
device		ppbus		# Parallel port bus (required)
device		lpt		# Printer
#device		plip		# TCP/IP over parallel
device		ppi		# Parallel port interface device
#device		vpo		# Requires scbus and da

# If you've got a "dumb" serial or parallel PCI card that is
# supported by the puc(4) glue driver, uncomment the following
# line to enable it (connects to the sio and/or ppc drivers):
#device         puc

# PCI Ethernet NICs.
device		de		# DEC/Intel DC21x4x (``Tulip'')
device		em		# Intel PRO/1000 adapter Gigabit Ethernet Card
device		txp		# 3Com 3cR990 (``Typhoon'')
device		vx		# 3Com 3c590, 3c595 (``Vortex'')

# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device		miibus		# MII bus support
#device		bfe		# Broadcom BCM440x 10/100 ethernet
#device		bge		# Broadcom BCM570xx Gigabit Ethernet
#device		dc		# DEC/Intel 21143 and various workalikes
#device		fxp		# Intel EtherExpress PRO/100B (82557, 82558)
#device		pcn		# AMD Am79C97x PCI 10/100 (precedence over 'lnc')
#device		re		# RealTek 8139C+/8169/8169S/8110S
device		rl		# RealTek 8129/8139
#device		sf		# Adaptec AIC-6915 (``Starfire'')
#device		sis		# Silicon Integrated Systems SiS 900/SiS 7016
#device		sk		# SysKonnect SK-984x and SK-982x gigabit ethernet
#device		ste		# Sundance ST201 (D-Link DFE-550TX)
#device		ti		# Alteon Networks Tigon I/II gigabit ethernet
#device		tl		# Texas Instruments ThunderLAN
#device		tx		# SMC EtherPower II (83c170 ``EPIC'')
#device		vr		# VIA Rhine, Rhine II
#device		wb		# Winbond W89C840F
device		xl		# 3Com 3c90x (``Boomerang'', ``Cyclone'')

# ISA Ethernet NICs.  pccard nics included.
#device		cs		# Crystal Semiconductor CS89x0 NIC
## 'device ed' requires 'device miibus'
#device		ed		# NE[12]000, SMC Ultra, 3c503, DS8390 cards
#device		ex		# Intel EtherExpress Pro/10 and Pro/10+
#device		ep		# Etherlink III based cards
#device		fe		# Fujitsu MB8696x based cards
#device		ie		# EtherExpress 8/16, 3C507, StarLAN 10 etc.
#device		lnc		# NE2100, NE32-VL Lance Ethernet cards
#device		sn		# SMC's 9000 series of ethernet chips
#device		xe		# Xircom pccard ethernet
#
## ISA devices that use the old ISA shims
##device		le
#
## Wireless NIC cards
#device		wlan		# 802.11 support
#device		an		# Aironet 4500/4800 802.11 wireless NICs. 
#device		awi		# BayStack 660 and others
#device		wi		# WaveLAN/Intersil/Symbol 802.11 wireless NICs.
##device		wl		# Older non 802.11 Wavelan wireless NIC.

# Pseudo devices - the number indicates how many units to allocate.
device		random		# Entropy device
device		loop		# Network loopback
device		ether		# Ethernet support
#device		sl		# Kernel SLIP
#device		ppp		# Kernel PPP
device		tun		# Packet tunnel.
device		pty		# Pseudo-ttys (telnet etc)
device		md		# Memory "disks"
#device		gif		# IPv6 and IPv4 tunneling
#device		faith		# IPv6-to-IPv4 relaying (translation)

# The `bpf' device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
device		bpf		# Berkeley packet filter

## USB support
#device		uhci		# UHCI PCI->USB interface
#device		ohci		# OHCI PCI->USB interface
#device		usb		# USB Bus (required)
##device		udbp		# USB Double Bulk Pipe devices
#device		ugen		# Generic
#device		uhid		# "Human Interface Devices"
#device		ukbd		# Keyboard
#device		ulpt		# Printer
#device		umass		# Disks/Mass storage - Requires scbus and da
#device		ums		# Mouse
#device		urio		# Diamond Rio 500 MP3 player
#device		uscanner	# Scanners
## USB Ethernet, requires mii
#device		aue		# ADMtek USB ethernet
#device		axe		# ASIX Electronics USB ethernet
#device		cue		# CATC USB ethernet
#device		kue		# Kawasaki LSI USB ethernet
#
## FireWire support
#device		firewire	# FireWire bus code
#device		sbp		# SCSI over FireWire (Requires scbus and da)
#device		fwe		# Ethernet over FireWire (non-standard!)
------------------------------------------------------------------------

>Fix:

As far as a _real_ fix... well... beats me!  I just work here.

The workaround is just to never disable the INET6 option in your kernel,
it seems.  (But that is a rather non-optimal solution I think.  What good
is an option if you can never exercise it?)
>Release-Note:
>Audit-Trail:
>Unformatted: