diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
index 644e99fc3..e537ea3d9 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -506,6 +506,12 @@ ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
 	unsigned char *data;
 	int islcp;
 
+	/* Ensure skb is not NULL and has at least 3 bytes */
+	if (!skb || skb->len < 3) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
 	data  = skb->data;
 	proto = get_unaligned_be16(data);