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-rw-r--r--mm/util.c47
1 files changed, 42 insertions, 5 deletions
diff --git a/mm/util.c b/mm/util.c
index 5f4bb59da63..7368479220b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1,20 +1,22 @@
#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.
+ * __kzalloc - allocate memory. The memory is set to zero.
* @size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*/
-void *kzalloc(size_t size, gfp_t flags)
+void *__kzalloc(size_t size, gfp_t flags)
{
- void *ret = kmalloc(size, flags);
+ void *ret = ____kmalloc(size, flags);
if (ret)
memset(ret, 0, size);
return ret;
}
-EXPORT_SYMBOL(kzalloc);
+EXPORT_SYMBOL(__kzalloc);
/*
* kstrdup - allocate space for and copy an existing string
@@ -31,9 +33,44 @@ char *kstrdup(const char *s, gfp_t gfp)
return NULL;
len = strlen(s) + 1;
- buf = kmalloc(len, gfp);
+ buf = ____kmalloc(len, gfp);
if (buf)
memcpy(buf, s, len);
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);