From 29a367af542828eadbf1e6e9a95b8b5312368edd Mon Sep 17 00:00:00 2001
From: Davi Arnaut <davi.arnaut@gmail.com>
Date: Fri, 24 Mar 2006 03:18:42 -0800
Subject: [PATCH] --- yaml --- r: 23473 b: refs/heads/master c:
 96840aa00a031069a136ec4c55d0bdd09ac6d3a7 h: refs/heads/master i:   23471:
 634de7fc6dee7f81428f9c8ced649c90dc4fe9dc v: v3

---
 [refs]                       |  2 +-
 trunk/include/linux/string.h |  2 ++
 trunk/mm/util.c              | 37 ++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index b87b562b1091..e01e4c2d0c80 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6687a97d4041f996f725902d2990e5de6ef5cbe5
+refs/heads/master: 96840aa00a031069a136ec4c55d0bdd09ac6d3a7
diff --git a/trunk/include/linux/string.h b/trunk/include/linux/string.h
index 369be3264a55..dee221429ad0 100644
--- a/trunk/include/linux/string.h
+++ b/trunk/include/linux/string.h
@@ -18,6 +18,8 @@ extern char * strsep(char **,const char *);
 extern __kernel_size_t strspn(const char *,const char *);
 extern __kernel_size_t strcspn(const char *,const char *);
 
+extern char *strndup_user(const char __user *, long);
+
 /*
  * Include machine specific inline routines
  */
diff --git a/trunk/mm/util.c b/trunk/mm/util.c
index 5f4bb59da63c..49e29f751b50 100644
--- a/trunk/mm/util.c
+++ b/trunk/mm/util.c
@@ -1,6 +1,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/module.h>
+#include <linux/err.h>
+#include <asm/uaccess.h>
 
 /**
  * kzalloc - allocate memory. The memory is set to zero.
@@ -37,3 +39,38 @@ char *kstrdup(const char *s, gfp_t gfp)
 	return buf;
 }
 EXPORT_SYMBOL(kstrdup);
+
+/*
+ * 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);