fail_function: switch to memdup_user_nul() helper

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

Link: https://lkml.kernel.org/r/20220826073337.2085798-1-yangyingliang@huawei.com
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 60dc825..03643e3 100644 (file)
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -247,15 +247,11 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
        /* cut off if it is too long */
        if (count > KSYM_NAME_LEN)
                count = KSYM_NAME_LEN;
-       buf = kmalloc(count + 1, GFP_KERNEL);
-       if (!buf)
-               return -ENOMEM;
 
-       if (copy_from_user(buf, buffer, count)) {
-               ret = -EFAULT;
-               goto out_free;
-       }
-       buf[count] = '\0';
+       buf = memdup_user_nul(buffer, count);
+       if (IS_ERR(buf))
+               return PTR_ERR(buf);
+
        sym = strstrip(buf);
 
        mutex_lock(&fei_lock);
@@ -308,7 +304,6 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
        }
 out:
        mutex_unlock(&fei_lock);
-out_free:
        kfree(buf);
        return ret;
 }