ptp: use memdup_user().

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 <falakreyaz@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 8 deletions

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 579fd65299a0..0b1ac6be69ce 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) {