Apply by doing:
cd /usr/src
patch -p0 < 001_mbuf.patch
Then build and install a new kernel.
This patch differs from the 4.0 patch because this issue was partly
fixed prior to 4.1 being tagged.
Index: sys/kern/uipc_mbuf2.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_mbuf2.c,v
retrieving revision 1.27
retrieving revision 1.27.2.1
diff -u -p -r1.27 -r1.27.2.1
--- sys/kern/uipc_mbuf2.c 26 Feb 2007 20:15:33 -0000 1.27
+++ sys/kern/uipc_mbuf2.c 28 Apr 2007 01:50:26 -0000 1.27.2.1
@@ -1,4 +1,4 @@
-/* $OpenBSD: uipc_mbuf2.c,v 1.27 2007/02/26 20:15:33 claudio Exp $ */
+/* $OpenBSD: uipc_mbuf2.c,v 1.27.2.1 2007/04/28 01:50:26 ckuethe Exp $ */
/* $KAME: uipc_mbuf2.c,v 1.29 2001/02/14 13:42:10 itojun Exp $ */
/* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
@@ -231,6 +231,8 @@ m_dup1(struct mbuf *m, int off, int len,
return (NULL);
if (off == 0 && (m->m_flags & M_PKTHDR) != 0) {
MGETHDR(n, wait, m->m_type);
+ if (n == NULL)
+ return (NULL);
M_DUP_PKTHDR(n, m);
l = MHLEN;
} else {
