Date: Sun, 6 Jul 1997 14:54:14 -0700 (PDT) From: terzis@cs..ucla.edu To: freebsd-gnats-submit@FreeBSD.ORG Subject: kern/4044: kernel crashes when ip_output() is called with a NULL route argument Message-ID: <199707062154.OAA07611@hub.freebsd.org> Resent-Message-ID: <199707062200.PAA07744@hub.freebsd.org>
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>Number: 4044
>Category: kern
>Synopsis: kernel crashes when ip_output() is called with a NULL route argument
>Confidential: no
>Severity: serious
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Jul 6 15:00:01 PDT 1997
>Last-Modified:
>Originator: Andreas Terzis
>Organization:
UCLA computer Science Dept
>Release: 2.2.2-RELEASE
>Environment:
FreeBSD pear.dnrc.bell-labs.com 2.2.2-RELEASE FreeBSD 2.2.2-RELEASE #1:
Thu Jul 3 19:08:37 EDT 1997 terzis@pear.dnrc.bell-labs.com:
/devel/MIP-kernel/sys/compile/RSVP+MIP-pear i386
>Description:
When ip_output() in netinet/ip_output.c is called with a NULL route
argument header the kernel crashes, because a test for a NULL argument
has been removed from this version of the code. You can find the test
in older versions of the sasme file or in the Stevens book
TCP/IP Illustrated Vol. II (page 230)
>How-To-Repeat:
try to hand a packet to ip_output for forwarding with a NULL route
argument.
>Fix:
Include a test for NULL route header.
This is what I have done and it worked:
/*
* IP output. The packet in mbuf chain m contains a skeletal IP
* header (with len, off, ttl, proto, tos, src, dst).
* The mbuf chain containing the packet will be freed.
* The mbuf opt, if present, will not be freed.
*/
int
ip_output(m0, opt, ro, flags, imo)
struct mbuf *m0;
struct mbuf *opt;
struct route *ro;
int flags;
struct ip_moptions *imo;
{
struct ip *ip, *mhip;
struct ifnet *ifp;
struct mbuf *m = m0;
int hlen = sizeof (struct ip);
int len, off, error = 0;
struct sockaddr_in *dst;
struct in_ifaddr *ia;
int isbroadcast;
struct route iproute; /* ADDED */
#ifdef DIAGNOSTIC
if ((m->m_flags & M_PKTHDR) == 0)
panic("ip_output no HDR");
if (!ro)
panic("ip_output no route, proto = %d",
mtod(m, struct ip *)->ip_p);
#endif
if (opt) {
m = ip_insertoptions(m, opt, &len);
hlen = len;
}
ip = mtod(m, struct ip *);
/*
* Fill in IP header.
*/
if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
ip->ip_vhl = IP_MAKE_VHL(IPVERSION, hlen >> 2);
ip->ip_off &= IP_DF;
ip->ip_id = htons(ip_id++);
ipstat.ips_localout++;
} else {
hlen = IP_VHL_HL(ip->ip_vhl) << 2;
}
/* ADDED test for NULL ro argument */
if (ro == 0) {
ro = &iproute;
bzero ((caddr_t) ro, sizeof(*ro));
}
>Audit-Trail:
>Unformatted:
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