[PATCH] ptp: use memdup_user().

[Muhammad Falak R Wani]

Use memdup_user to duplicate a memory region from user-space to
kernel-space, instead of open coding using kmalloc & copy_from_user.

Signed-off-by: Muhammad Falak R Wani <falakre...@gmail.com>
---
 drivers/ptp/ptp_chardev.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 579fd65..0b1ac6b 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -208,14 +208,9 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, 
unsigned long arg)
                break;
 
        case PTP_SYS_OFFSET:
-               sysoff = kmalloc(sizeof(*sysoff), GFP_KERNEL);
-               if (!sysoff) {
-                       err = -ENOMEM;
-                       break;
-               }
-               if (copy_from_user(sysoff, (void __user *)arg,
-                                  sizeof(*sysoff))) {
-                       err = -EFAULT;
+               sysoff = memdup_user((void __user *)arg, sizeof(*sysoff));
+               if (IS_ERR(sysoff)) {
+                       err = PTR_ERR(sysoff);
                        break;
                }
                if (sysoff->n_samples > PTP_MAX_SAMPLES) {
-- 
1.9.1