[Midnightbsd-cvs] src [12124] trunk/sys/netinet/ip_icmp.c: ICMP buffer underwrite

[laffer1 at midnightbsd.org]

Revision: 12124
          http://svnweb.midnightbsd.org/src/?rev=12124
Author:   laffer1
Date:     2018-11-30 15:23:43 -0500 (Fri, 30 Nov 2018)
Log Message:
-----------
ICMP buffer underwrite

The icmp_error routine allocates either an mbuf or a cluster depending on the
size of the data to be quoted in the ICMP reply, but the calculation failed
to account for additional padding on 64-bit platforms when using a
non-default sysctl value for net.inet.icmp.quotelen.

Modified Paths:
--------------
    trunk/sys/netinet/ip_icmp.c

Modified: trunk/sys/netinet/ip_icmp.c
===================================================================
--- trunk/sys/netinet/ip_icmp.c	2018-11-25 20:40:09 UTC (rev 12123)
+++ trunk/sys/netinet/ip_icmp.c	2018-11-30 20:23:43 UTC (rev 12124)
@@ -294,7 +294,8 @@
 	mac_netinet_icmp_reply(n, m);
 #endif
 	icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
-	m_align(m, ICMP_MINLEN + icmplen);
+	m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
+	m->m_data += sizeof(struct ip);
 	m->m_len = ICMP_MINLEN + icmplen;
 
 	/* XXX MRT  make the outgoing packet use the same FIB
@@ -336,6 +337,8 @@
 	 * reply should bypass as well.
 	 */
 	m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
+	KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
+	    ("insufficient space for ip header"));
 	m->m_data -= sizeof(struct ip);
 	m->m_len += sizeof(struct ip);
 	m->m_pkthdr.len = m->m_len;