From 050145f45590afa8ef3f39e743d2d5d71af0645c Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Tue, 31 Mar 2009 15:23:16 -0700
Subject: [PATCH] --- yaml --- r: 139154 b: refs/heads/master c:
 610a77e04a8d9fe8764dc484e2182fa251ce1cc2 h: refs/heads/master v: v3

---
 [refs]                       |  2 +-
 trunk/include/linux/string.h |  1 +
 trunk/mm/util.c              | 30 ++++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 8752f9b10d11..3807964982a3 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e2f17d9459aeccf4e013e31cbd741d6b1858eec4
+refs/heads/master: 610a77e04a8d9fe8764dc484e2182fa251ce1cc2
diff --git a/trunk/include/linux/string.h b/trunk/include/linux/string.h
index d18fc198aa2f..8852739f36df 100644
--- a/trunk/include/linux/string.h
+++ b/trunk/include/linux/string.h
@@ -12,6 +12,7 @@
 #include <linux/stddef.h>	/* for NULL */
 
 extern char *strndup_user(const char __user *, long);
+extern void *memdup_user(const void __user *, size_t);
 
 /*
  * Include machine specific inline routines
diff --git a/trunk/mm/util.c b/trunk/mm/util.c
index 37eaccdf3054..7c122e49f769 100644
--- a/trunk/mm/util.c
+++ b/trunk/mm/util.c
@@ -69,6 +69,36 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp)
 }
 EXPORT_SYMBOL(kmemdup);
 
+/**
+ * memdup_user - duplicate memory region from user space
+ *
+ * @src: source address in user space
+ * @len: number of bytes to copy
+ *
+ * Returns an ERR_PTR() on failure.
+ */
+void *memdup_user(const void __user *src, size_t len)
+{
+	void *p;
+
+	/*
+	 * Always use GFP_KERNEL, since copy_from_user() can sleep and
+	 * cause pagefault, which makes it pointless to use GFP_NOFS
+	 * or GFP_ATOMIC.
+	 */
+	p = kmalloc_track_caller(len, GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	if (copy_from_user(p, src, len)) {
+		kfree(p);
+		return ERR_PTR(-EFAULT);
+	}
+
+	return p;
+}
+EXPORT_SYMBOL(memdup_user);
+
 /**
  * __krealloc - like krealloc() but don't free @p.
  * @p: object to reallocate memory for.