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[src/netbsd-8]: src/sys/netinet Pull up following revision(s) (requested by m...
details: https://anonhg.NetBSD.org/src/rev/9325694f297f
branches: netbsd-8
changeset: 434800:9325694f297f
user: martin <martin%NetBSD.org@localhost>
date: Sat Mar 31 10:38:53 2018 +0000
description:
Pull up following revision(s) (requested by maxv in ticket #675):
sys/netinet/ip_icmp.c: revision 1.168
Fix a possible buffer overflow in the IPv4 _ctlinput functions.
In _icmp_input we are guaranteeing that the ICMP_ADVLENMIN-byte area
starting from 'icp' is contiguous.
ICMP_ADVLENMIN = 8 + sizeof(struct ip) + 8 = 36
But the _ctlinput functions (eg udp_ctlinput) expect the area to be
larger. These functions read at:
(uint8_t *)icp + 8 + (icp->icmp_ip.ip_hl << 2)
which can be crafted to be:
(uint8_t *)icp + 68
So we end up reading 'icp+68' while the valid area ended at 'icp+36'.
Having said that, it seems pretty complicated to trigger this bug; it
would have to be a fragmented packet with half of the ICMP header in the
first fragment, and we would need to have a driver that did not allocate
a cluster for the first mbuf of the chain.
The check of icmplen against ICMP_ADVLEN(icp) was not sufficient: while it
did guarantee that the ICMP header fit the chain, it did not guarantee
that it fit 'm'.
Fix this bug by pulling up to hlen+ICMP_ADVLEN(icp). No need to log an
error. Rebase the pointers afterwards.
diffstat:
sys/netinet/ip_icmp.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diffs (33 lines):
diff -r 38e9bb1509df -r 9325694f297f sys/netinet/ip_icmp.c
--- a/sys/netinet/ip_icmp.c Sat Mar 31 10:32:05 2018 +0000
+++ b/sys/netinet/ip_icmp.c Sat Mar 31 10:38:53 2018 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: ip_icmp.c,v 1.161 2017/03/31 06:49:44 ozaki-r Exp $ */
+/* $NetBSD: ip_icmp.c,v 1.161.6.1 2018/03/31 10:38:53 martin Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -94,7 +94,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip_icmp.c,v 1.161 2017/03/31 06:49:44 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip_icmp.c,v 1.161.6.1 2018/03/31 10:38:53 martin Exp $");
#ifdef _KERNEL_OPT
#include "opt_ipsec.h"
@@ -541,6 +541,14 @@
ICMP_STATINC(ICMP_STAT_BADLEN);
goto freeit;
}
+ if (m->m_len < hlen + ICMP_ADVLEN(icp)) {
+ m = m_pullup(m, hlen + ICMP_ADVLEN(icp));
+ if (m == NULL)
+ goto freeit;
+ }
+ ip = mtod(m, struct ip *);
+ icp = (struct icmp *)(mtod(m, uint8_t *) + hlen);
+
if (IN_MULTICAST(icp->icmp_ip.ip_dst.s_addr))
goto badcode;
#ifdef ICMPPRINTFS
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