diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 61e6f0d..3b924ec 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/ctype.h>
+#include <errno.h>
 
 #include <common.h>
 #if !defined (CONFIG_PANIC_HANG)
@@ -61,6 +62,56 @@
 	return result;
 }
 
+/**
+ * strict_strtoul - convert a string to an unsigned long strictly
+ * @cp: The string to be converted
+ * @base: The number base to use
+ * @res: The converted result value
+ *
+ * strict_strtoul converts a string to an unsigned long only if the
+ * string is really an unsigned long string, any string containing
+ * any invalid char at the tail will be rejected and -EINVAL is returned,
+ * only a newline char at the tail is acceptible because people generally
+ * change a module parameter in the following way:
+ *
+ *      echo 1024 > /sys/module/e1000/parameters/copybreak
+ *
+ * echo will append a newline to the tail.
+ *
+ * It returns 0 if conversion is successful and *res is set to the converted
+ * value, otherwise it returns -EINVAL and *res is set to 0.
+ *
+ * simple_strtoul just ignores the successive invalid characters and
+ * return the converted value of prefix part of the string.
+ *
+ * Copied this function from Linux 2.6.38 commit ID:
+ * 521cb40b0c44418a4fd36dc633f575813d59a43d
+ *
+ */
+int strict_strtoul(const char *cp, unsigned int base, unsigned long *res)
+{
+	char *tail;
+	unsigned long val;
+	size_t len;
+
+	*res = 0;
+	len = strlen(cp);
+	if (len == 0)
+		return -EINVAL;
+
+	val = simple_strtoul(cp, &tail, base);
+	if (tail == cp)
+		return -EINVAL;
+
+	if ((*tail == '\0') ||
+		((len == (size_t)(tail - cp) + 1) && (*tail == '\n'))) {
+		*res = val;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 long simple_strtol(const char *cp,char **endp,unsigned int base)
 {
 	if(*cp=='-')