powerpc/nvram: use memdup_user

Use memdup_user() helper instead of open-coding to simplify the code.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index eae61b044e9e3510657a4777d59c4dc0bbd06267..496d6393bd41824b565c66b731e1b4147c7e3923 100644 (file)
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -792,21 +792,17 @@ static ssize_t dev_nvram_write(struct file *file, const char __user *buf,
        count = min_t(size_t, count, size - *ppos);
        count = min(count, PAGE_SIZE);
 
-       ret = -ENOMEM;
-       tmp = kmalloc(count, GFP_KERNEL);
-       if (!tmp)
-               goto out;
-
-       ret = -EFAULT;
-       if (copy_from_user(tmp, buf, count))
+       tmp = memdup_user(buf, count);
+       if (IS_ERR(tmp)) {
+               ret = PTR_ERR(tmp);
                goto out;
+       }
 
        ret = ppc_md.nvram_write(tmp, count, ppos);
 
-out:
        kfree(tmp);
+out:
        return ret;
-
 }
 
 static long dev_nvram_ioctl(struct file *file, unsigned int cmd,