Date: Thu, 12 Dec 2002 00:54:48 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: Alexander Langer <alex@big.endian.de> Cc: Patrick Soltani <psoltani@ultradns.com>, freebsd-hackers@FreeBSD.ORG, luigi@FreeBSD.ORG Subject: Re: panic: icmp_error: bad length Message-ID: <200212120054.aa55340@salmon.maths.tcd.ie> In-Reply-To: Your message of "Thu, 12 Dec 2002 00:32:46 %2B0100." <20021211233246.GR64335@fump.kawo2.rwth-aachen.de>
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In message <20021211233246.GR64335@fump.kawo2.rwth-aachen.de>, Alexander Langer
writes:
>Yeah, same situation here. 4.6 used to work w/o problem, 4.7 doesn't.
Great, thanks for the debugging info. The bug seems to be that
icmp_error() requires that the IP header fields are in host order,
but when it is called on a briged packet by the IPFW code, this is
not the case. Something like the patch below (untested) should fix
the IPFW1 case. A similar change is needed for IPFW2.
Luigi: does this look reasonable? I'm not familiour enough with the
IPFW code to know if it is OK to modify the mbuf like this. If not
then it needs to be copied first like ip_forward() does, making
sure that the IP header does not end up in a shared cluster.
Ian
Index: ip_fw.c
===================================================================
RCS file: /home/iedowse/CVS/src/sys/netinet/ip_fw.c,v
retrieving revision 1.131.2.38
diff -u -r1.131.2.38 ip_fw.c
--- ip_fw.c 21 Nov 2002 01:27:30 -0000 1.131.2.38
+++ ip_fw.c 12 Dec 2002 00:43:22 -0000
@@ -1573,6 +1573,11 @@
break;
}
default: /* Send an ICMP unreachable using code */
+ /* Must convert to host order for icmp_error(). */
+ if (BRIDGED) {
+ NTOHS(ip->ip_len);
+ NTOHS(ip->ip_off);
+ }
icmp_error(*m, ICMP_UNREACH,
f->fw_reject_code, 0L, 0);
*m = NULL;
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