convert a bunch of open-coded instances of memdup_user_nul()

A _lot_ of ->write() instances were open-coding it; some are
converted to memdup_user_nul(), a lot more remain...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 8 deletions

diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c
index 0fdedadff7bc..2a67b496a9e2 100644
--- a/drivers/s390/char/vmcp.c
+++ b/drivers/s390/char/vmcp.c
@@ -88,14 +88,9 @@ vmcp_write(struct file *file, const char __user *buff, size_t count,
 
         if (count > 240)
                 return -EINVAL;
-        cmd = kmalloc(count + 1, GFP_KERNEL);
-        if (!cmd)
-                return -ENOMEM;
-        if (copy_from_user(cmd, buff, count)) {
-                kfree(cmd);
-                return -EFAULT;
-        }
-        cmd[count] = '\0';
+        cmd = memdup_user_nul(buff, count);
+        if (IS_ERR(cmd))
+                return PTR_ERR(cmd);
         session = file->private_data;
         if (mutex_lock_interruptible(&session->mutex)) {
                 kfree(cmd);