caif: Bugfix - handle mem-allocation failures

Discovered bugs when injecting slab allocation failures.
Add checks on all memory allocation.

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/caif/cfserl.c b/net/caif/cfserl.c
index 06029ea..cb4325a 100644
--- a/net/caif/cfserl.c
+++ b/net/caif/cfserl.c
@@ -67,6 +67,8 @@
 		layr->incomplete_frm =
 		    cfpkt_append(layr->incomplete_frm, newpkt, expectlen);
 		pkt = layr->incomplete_frm;
+		if (pkt == NULL)
+			return -ENOMEM;
 	} else {
 		pkt = newpkt;
 	}
@@ -154,7 +156,6 @@
 			if (layr->usestx) {
 				if (tail_pkt != NULL)
 					pkt = cfpkt_append(pkt, tail_pkt, 0);
-
 				/* Start search for next STX if frame failed */
 				continue;
 			} else {