new primitive: vmemdup_user()
similar to memdup_user(), but does *not* guarantee that result will
be physically contiguous; use only in cases where that's not a requirement
and free it with kvfree().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/util.c b/mm/util.c
index 4b93ffa..c125050 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -150,7 +150,8 @@ EXPORT_SYMBOL(kmemdup_nul);
* @src: source address in user space
* @len: number of bytes to copy
*
- * Returns an ERR_PTR() on failure.
+ * Returns an ERR_PTR() on failure. Result is physically
+ * contiguous, to be freed by kfree().
*/
void *memdup_user(const void __user *src, size_t len)
{
@@ -169,6 +170,32 @@ void *memdup_user(const void __user *src, size_t len)
}
EXPORT_SYMBOL(memdup_user);
+/**
+ * vmemdup_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. Result may be not
+ * physically contiguous. Use kvfree() to free.
+ */
+void *vmemdup_user(const void __user *src, size_t len)
+{
+ void *p;
+
+ p = kvmalloc(len, GFP_USER);
+ if (!p)
+ return ERR_PTR(-ENOMEM);
+
+ if (copy_from_user(p, src, len)) {
+ kvfree(p);
+ return ERR_PTR(-EFAULT);
+ }
+
+ return p;
+}
+EXPORT_SYMBOL(vmemdup_user);
+
/*
* strndup_user - duplicate an existing string from user space
* @s: The string to duplicate
