s390/keyboard: use memdup_user_nul()

Use memdup_user_nul to duplicate a memory region from user-space
to kernel-space and terminate with a NULL, instead of open coding
using kmalloc + copy_from_user and explicitly NULL terminating.

Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com>
[heiko.carstens@de.ibm.com: remove comment]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c
index ef04a9f..7b9c50a 100644 (file)
--- a/drivers/s390/char/keyboard.c
+++ b/drivers/s390/char/keyboard.c
@@ -438,18 +438,9 @@ do_kdgkb_ioctl(struct kbd_data *kbd, struct kbsentry __user *u_kbs,
                        return -EFAULT;
                if (len > sizeof(u_kbs->kb_string))
                        return -EINVAL;
-               p = kmalloc(len, GFP_KERNEL);
-               if (!p)
-                       return -ENOMEM;
-               if (copy_from_user(p, u_kbs->kb_string, len)) {
-                       kfree(p);
-                       return -EFAULT;
-               }
-               /*
-                * Make sure the string is terminated by 0. User could have
-                * modified it between us running strnlen_user() and copying it.
-                */
-               p[len - 1] = 0;
+               p = memdup_user_nul(u_kbs->kb_string, len);
+               if (IS_ERR(p))
+                       return PTR_ERR(p);
                kfree(kbd->func_table[kb_func]);
                kbd->func_table[kb_func] = p;
                break;