Index: uipc_socket.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket.c,v
retrieving revision 1.135
diff -u -p -r1.135 uipc_socket.c
--- uipc_socket.c	11 Dec 2014 19:21:57 -0000	1.135
+++ uipc_socket.c	22 Dec 2014 01:11:03 -0000
@@ -493,15 +493,18 @@ restart:
 					mlen = MLEN;
 				}
 				if (resid >= MINCLSIZE && space >= MCLBYTES) {
-					MCLGET(m, M_NOWAIT);
+					MCLGETI(m, M_NOWAIT, NULL, lmin(resid,
+					    lmin(space, MAXMCLBYTES)));
 					if ((m->m_flags & M_EXT) == 0)
 						goto nopages;
 					if (atomic && top == 0) {
-						len = lmin(MCLBYTES - max_hdr,
-						    resid);
+						len = lmin(resid,
+						    m->m_ext.ext_size -
+						    max_hdr);
 						m->m_data += max_hdr;
 					} else
-						len = lmin(MCLBYTES, resid);
+						len = lmin(resid,
+						    m->m_ext.ext_size);
 					space -= len;
 				} else {
 nopages: