[PATCH 3.10 39/62] autofs4 copy_dev_ioctl(): keep the value of ->size wed used for allocation

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 0a280962dc6e117e0e4baa668453f753579265d9 upstream.

X-Coverup: just ask spender
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/autofs4/dev-ioctl.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -95,7 +95,7 @@ static int check_dev_ioctl_version(int c
  */
 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
 {
-	struct autofs_dev_ioctl tmp;
+	struct autofs_dev_ioctl tmp, *res;
 
 	if (copy_from_user(&tmp, in, sizeof(tmp)))
 		return ERR_PTR(-EFAULT);
@@ -103,7 +103,11 @@ static struct autofs_dev_ioctl *copy_dev
 	if (tmp.size < sizeof(tmp))
 		return ERR_PTR(-EINVAL);
 
-	return memdup_user(in, tmp.size);
+	res = memdup_user(in, tmp.size);
+	if (!IS_ERR(res))
+		res->size = tmp.size;
+
+	return res;
 }
 
 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)


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