+
+/**
+ * kmemdup - duplicate region of memory
+ *
+ * @src: memory region to duplicate
+ * @len: memory region length
+ * @gfp: GFP mask to use
+ */
+void *kmemdup(const void *src, size_t len, gfp_t gfp)
+{
+ void *p;
+
+ p = kmalloc_track_caller(len, gfp);
+ if (p)
+ memcpy(p, src, len);
+ return p;
+}
+EXPORT_SYMBOL(kmemdup);
+
+/*
+ * strndup_user - duplicate an existing string from user space
+ *
+ * @s: The string to duplicate
+ * @n: Maximum number of bytes to copy, including the trailing NUL.
+ */
+char *strndup_user(const char __user *s, long n)
+{
+ char *p;
+ long length;
+
+ length = strnlen_user(s, n);
+
+ if (!length)
+ return ERR_PTR(-EFAULT);
+
+ if (length > n)
+ return ERR_PTR(-EINVAL);
+
+ p = kmalloc(length, GFP_KERNEL);
+
+ if (!p)
+ return ERR_PTR(-ENOMEM);
+
+ if (copy_from_user(p, s, length)) {
+ kfree(p);
+ return ERR_PTR(-EFAULT);
+ }
+
+ p[length - 1] = '\0';
+
+ return p;
+}
+EXPORT_SYMBOL(strndup_user);