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Date: Wed, 29 Nov 2000 19:34:49 -0800 (PST)
From: ming@unixbox.com
To: freebsd-gnats-submit@FreeBSD.org
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Subject: kern/23187: possible panic when ipfw is used on ICMP on 4.2-stable
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>Number:         23187
>Category:       kern
>Synopsis:       possible panic when ipfw is used on ICMP on 4.2-stable
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Nov 29 19:40:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Ming Zhang
>Release:        4.2-stable
>Organization:
>Environment:
FreeBSD bluerose.windmoon.nu 4.2-STABLE FreeBSD 4.2-STABLE #27: Tue Nov 28 23:21:47 PST 2000     fengyue@bluerose.windmoon.nu:/usr/src/sys/compile/bluerose  i386
b
>Description:
the ofin struct passed into fr_makefrip() from ip_state.c is created
on the local function stack and its fin_v member is not init'ed.
fr_makefrip() checks fin_v to determine wether to execute IPV6 code
or IPV4 code, however fin_v's value is undetermined and thus it's
possible it may contain 6 while the packet (ip_t) is a IPV4 packet,
and this may cause kernel to panic sometimes (Happened once to me already)
>How-To-Repeat:
tough to reproduce the crash but very easy to get fr_makefrip() to
execute IPV6 code when dealing with IPV4 ICMP packets.  Simply
keep doing traceroute to some hosts on the net, evetually fin_v may
contain the value 6
>Fix:
change v = fin->fin_v; to v = fin->fin_v = ip->ip_v;

the patch is at http://www.windmoon.nu/mypatch


>Release-Note:
>Audit-Trail:
>Unformatted:


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